[User]
Hey, I'm looking to design a parametric star knob in OpenSCAD, and I'd like it to have some specific features, including some nice, smooth curves. I'm thinking along the lines of a design where the main handle part has a star-like shape with rounded points and indents, and then it connects to a cylindrical base. The knob should also have a hole for a bolt, with an optional counterbore for the bolt head.

Here's a more detailed breakdown of what I'm after:

**Handle:**

*   **Star Shape:** The handle should have a star-like shape, with the number of points being a parameter I can control. I'd like the points to be rounded.
*   **Outer Diameter:** I need to be able to specify the diameter of the outer points of the star.
*   **Inner Diameter:** I need to control the diameter of the "indents" between the star points. This might be the diameter of the circular indent, or the distance across the flat sides if no circle.
*   **Point Radius:** Each of the star points should have a circular radius at the tip which I should be able to specify.
*   **Thickness:** The handle should have a specified vertical thickness.
*   **Fillets:** I'd like to have rounded edges (fillets) at the top and bottom of the handle, with separate radius parameters for each. These fillets should be continuous all the way around.

**Base:**

*   **Diameter:** I need to be able to control the diameter of the base cylinder. This will be the mating surface that tightens against other parts.
*   **Height:** The height of the base should be adjustable. This is the distance from the bottom of the knob to where the handle begins.
*   **Transition Fillet:** There should be a fillet between the base cylinder and the handle, with its radius being a parameter. I would expect this to work regardless of the relative diameters of the handle and base.

**Bolt Hole:**

*   **Diameter:** A parameter for the diameter of the bolt hole. This should fit the bolt shank.
*   **Optional Head/Nut:** I'd like the option to have a counterbore for a bolt head or a nut. This should be optional, such that if no head/nut is needed there would just be a hole for a shaft.
*   **Head/Nut Diameter:** If a counterbore is desired, it needs a parameter for the diameter of the bolt head or nut.
*   **Head/Nut Thickness:** And a parameter for the thickness of the bolt head or nut.
*   **Head/Nut Height:** This would be the depth of the bolt hole from the bottom of the base up to the bottom of the bolt head or nut.
*   **Head/Nut Sides:** A parameter to control the number of sides (e.g., 6 for a hex head bolt, 4 for a square nut).
*   **Counterbore Diameter:** Allow an override for the counterbore diameter - if set to 0 then a default counterbore would be calculated based on bolt head diameter.
*   **Counterbore Fillet:** Allow for a fillet on the top edge of the counterbore.

**Other:**

*   **Resolution:** It would be great to have a resolution parameter that controls the smoothness of curves. I'm imagining this would correspond with `$fs`.

I think that covers it. I am not looking for you to improve upon an existing file, but rather to write the necessary file from scratch. I'm not worried about performance at this stage, I'd rather the solution be readable and easy to understand. Let me know if you have any questions. I'm hoping for a single `.scad` file for all of the code.

[Assistant]
StarKnob-legacy.scad:
```
/* [Knob Handle] */
// Number of points on the star
points = 3; // [3:20]
// Diameter of the outermost tip of knob handle
handleOuterDiameter = 75;
// Diameter of the innermost indent in the knob handle
handleInnerDiameter = 30;
// Radius of the star points
pointRadius = 10;

// Vertical thickness of knob handle
handleThickness = 15;
// Radius of top fillet, forms rounded edge all around top of handle
rTopFillet = 10;
// Radius of bottom fillet, forms rounded edge all around bottom of handle
rBottomFillet = 2;

/* [Knob Base] */
// Diameter of the base, this comprises the mating surface when knob is tightended
baseDiameter = 20;
// Distance from bottom of knob base to underside of handle
baseHeight = 15;
// Radius of fillet between handle and base of knob.  Recommended less than or equal to Base Height.
rTransitionFillet = 10;

/* [Bolt Hole] */
// Diameter of bolt hole.  Fits bolt shank, or plain round shaft.
boltDiameter = 8.4;
// Diameter of bolt head.  Size across flats (wrench size). Set to zero if no head (shaft hole only).
boltHeadDiameter = 13; //
// Thickness of the bolt head (or nut). Set to zero if no head (shaft hole only).
boltHeadThickness = 5.5;
// Distance from base of knob to bottom of bolt head (how much thread is inside of knob)
boltHeadHeight = 5;
// Number of sides on bolt head (or nut) (6 for hex head bolt, 4 for carriage bolt, for example)
boltHeadSides = 6;
// Diameter of counterbore, which the bolt head should fit freely inside.  If 0 then a default hex-head counterbore will be automatically calculated as (boltHeadDiameter * 2/sqrt(3) + 1)
boltCounterboreDiameter = 0;
// Radius of rounded edge at top of counterbore
rCounterboreFillet = 2;
/* [Other] */
// Resolution in mm.  This model can take a long time to generate, especially at high detail.  To keep things responsive use a coarse (higher numeric value) resolution while making changes, then change to a finer setting just before clicking "Create Thing" and generating the model.
resolution = 0.75; // [0.2:0.05:5]

/* [Hidden] */
$fs=resolution;
$fa=1;

counterboreDiameter = boltCounterboreDiameter == 0 ? boltHeadDiameter * 2/sqrt(3) + 1 : boltCounterboreDiameter;

starKnob(points, handleOuterDiameter, handleInnerDiameter, pointRadius, handleThickness);

function calculateR4(r1,r2,r3,th) = (pow(r1,2)-2*r3*cos(th)*(r1-r2)-2*r1*r2+pow(r3,2))/(2*(cos(th)*(r1-r2)+r2-r3));
function calculateB(r2,r3,r4,th) = asin((r3+r4)*sin(th)/(r2+r4));

// a knob with profile of continuous circular curves
module starKnob(points, handleOuterDiameter, handleInnerDiameter, pointRadius, handleThickness) {
  th = 180/points;
  r1 = handleOuterDiameter/2;
  r2 = pointRadius;
  r3 = handleInnerDiameter/2;
  r4 = calculateR4(r1,r2,r3,th);
  Btemp1 = calculateB(r2,r3,r4,th);
  Btemp2 = calculateB(r2,r3+0.001,calculateR4(r1,r2,r3+0.001,th),th);
  B = Btemp2 > Btemp1 ? Btemp1 : 180 - Btemp1;
  A = 180 - th - B;
  err = 0.002;

  r5 = sqrt( pow(r1-r2,2)+pow(r2,2)-2*(r1-r2)*r2*cos(B));
  r3Max = ((r1-r2)*cos(th)+r2);
  //echo("A",A,"B",B);
  echo("r1",r1,"r2",r2,"r3",r3,"r4",r4,"r5",r5);
  //echo("Btemp2", Btemp2, "Btemp1",Btemp1);

  //echo(r3Max);
  bottomDiameter = ((r4 > 0) ? handleInnerDiameter : r3Max*2) - rBottomFillet * 2;
  rBottomFillet2 = (baseDiameter - bottomDiameter) / 2;
  xBaseFillet = baseDiameter / 2 - rBottomFillet2;

  difference() {
    union() {

      // ================ HANDLE + TRANSITION ===============
      difference() {
        intersection() {
          union() {
            translate([0,0,-min(baseHeight,rTransitionFillet)-err]) linear_extrude(handleThickness+min(baseHeight,rTransitionFillet)+2*err, convexity=6) difference() {
              union() {
                if (r3 >= r3Max) {
                  intersection() {
                    circle(r=r3Max/cos(th),$fn=points);
                    rotate([0,0,th])circle(r=(r1-r2+r2*cos(th))/cos(th),$fn=points);
                  }
                } else {
                  circle(r=r5);
                }
                for (i=[1:points]) rotate(2*i*th) translate([r1 - r2,0]) circle(r=r2);
              }
              if (r4>0) {
                for (i=[1:points]) rotate((2*i+1)*th) translate([r3+r4,0]) circle(r=r4);
              }
            }
          }

          union() {
            // outer handle bounds cylinder
            cylinder(r=r1+err, h=handleThickness+err);
            // base transition fillet
            if (rTransitionFillet > 0) translate([0,0,-rTransitionFillet]) {
              fil_polar_i(-baseDiameter/2, rTransitionFillet, 360, baseDiameter/2, handleThickness+err);
            }
          }
        }

        //render(convexity=points+2) {
          // Cutouts to create smooth handle edges
          if (r4>0) { // indents in between star points
              for (i=[1:points]) {
                if (rTopFillet > 0) {
                  // top fillet cutouts
                  rotate((2*i-1)*th) translate([r3+r4,0,handleThickness-rTopFillet])
                    rotate([0,0,180]) fil_polar_i(-r4, rTopFillet, 2*A+0.01, r4,0.1);
                  rotate(2*i*th) translate([r1-r2,0,handleThickness-rTopFillet])
                    fil_polar_i(r2, rTopFillet, 2*(180-B)+0.01, $fs/5,$fs/5);
                }
                if (rBottomFillet > 0) {
                  // bottom fillet cutouts
                  rotate((2*i-1)*th) translate([r3+r4,0,rBottomFillet])
                    translate([0,0,]) rotate([180,0,180]) fil_polar_i(-r4, rBottomFillet, 2*A+0.01, r4, rTransitionFillet+err);
                  rotate(2*i*th) translate([r1-r2,0,rBottomFillet])
                    rotate([180,0,0]) fil_polar_i(r2, rBottomFillet, 2*(180-B)+0.01, $fs/5, rTransitionFillet+err);
                }
              }
          } else { // no indent, flat sides
            for (i=[1:points]) {
              if (rTopFillet > 0) {
                rotate((2*i+1)*th-90) translate([handleOuterDiameter/2,r3Max-rTopFillet,handleThickness-rTopFillet])
                  rotate([0,0,180]) fil_linear_i(handleOuterDiameter, rTopFillet, 90, $fs/5, $fs/5, false);
                rotate(2*i*th) translate([r1-r2,0,handleThickness-rTopFillet])
                  rotate([0,0]) fil_polar_i(r2, rTopFillet, 360/points, $fs/5, $fs/5, true);
              }
              if (rBottomFillet > 0) {
                rotate((2*i+1)*th+90) translate([handleOuterDiameter/2,-r3Max+rBottomFillet,rBottomFillet])
                  rotate([180,0,180]) fil_linear_i(handleOuterDiameter, rBottomFillet,90, rTransitionFillet+err, handleOuterDiameter/2, false);
                rotate(2*i*th) translate([r1-r2,0,rBottomFillet])
                  rotate([180,0]) fil_polar_i(r2, rBottomFillet, 360/points, $fs/5, rTransitionFillet+err, true);
              }
            }
          }
        //}
      }

      // =============== BASE ===============
      // base cylinder
      translate([0,0,-baseHeight]) cylinder(d=baseDiameter, h=baseHeight-rTransitionFillet+err);

      // reverse transition fillet for bases larger than bottom of handle
      if (baseDiameter > bottomDiameter && rTransitionFillet > 0)
        rotate([180,0,180]) fil_polar_i(-xBaseFillet, rBottomFillet2, 360, err, err, false, min(baseHeight,rTransitionFillet) + err);
    }

    // ================ BOLT =================
    // bolt shank cutout
    if (boltHeadHeight > 0)
      translate([0,0,-baseHeight-1]) cylinder(d=boltDiameter, h=boltHeadHeight+1+err);

    if (boltHeadDiameter > 0 && boltHeadThickness > 0) {
      // bolt counterbore
      translate([0,0,-baseHeight+boltHeadHeight+boltHeadThickness-err]) cylinder(d=counterboreDiameter, h=baseHeight+handleThickness+2*err);
      // hex cap cutout
      translate([0,0,-baseHeight+boltHeadHeight-err]) cylinder(d=boltHeadDiameter*2/sqrt(3), h=boltHeadThickness+2*err, $fn=boltHeadSides);
      // rounded counterbore edge
      if (rCounterboreFillet > 0)
        translate([0,0,handleThickness-rCounterboreFillet]) fil_polar_i(-counterboreDiameter/2,rCounterboreFillet,360,1,1);
    }

  }

  /*
  // show inner and outer diameter
  translate([0,0,20]) {
    color([1,0,0,0.2]) linear_extrude(1)
      for (i=[0:points-1]) rotate([0,0,360/points * i]) translate([r5,0]) circle(r=r2);
    color([0,1,0,0.3]) linear_extrude(1) difference() {
        circle(r=r1);
        circle(r=r3);
        for (i=[0:points-1]) rotate([0,0,360/points * i]) translate([r5,0]) circle(r=r2);
      }
    color([0,0,1,0.25]) linear_extrude(1) circle(r=r3);
  }
  */

}

module angle_cut(angle=90,size=1000) {
  x = size*cos(angle/2);
  y = size*sin(angle/2);
  translate([0,0,-size])
    linear_extrude(2*size) polygon([[0,0],[x,y],[x,size],[-size,size],[-size,-size],[x,-size],[x,-y]]);
}

// 2d primitive for inside fillets.
module fil_2d_i(r1, angle=90, extendX=0, extendY=0, halfAlign=false, r2=0) {
  //echo(r1, r2, angle, extendX, extendY);
  r = max(r1,r2);
  s1 = (r2 == 0) ? 1 : ((r2 > r1) ? r1/r2 : 1);
  s2 = (r2 == 0) ? 1 : ((r2 > r1) ? 1 : r2/r1);
  x1 = r + extendX;
  y1 = r + extendY;
  x2 = r * sin(angle);
  y2 = r * cos(angle);
  scale([s1,s2]) difference() {
    polygon((angle > 180) ?
      [[0,0],[0,y1],[x1,y1],[x1,-r],[x2,-r]]:
      [[0,0],[0,y1],[x1,y1],[x1,y2],[x2,y2]]
    );
    rotate(halfAlign ? 90 : 0) circle(r=max(r2,r));
  }
}

// 3d polar inside fillet.
module fil_polar_i(R, r, angle=90, extendX=0,extendY=0, halfAlign=false, r2=0) {

  // support for angle parameter in rotate_extrude was added after release 2015.03
  // Thingiverse customizer is still on 2015.03
  angleSupport = (version_num() > 20150399) ? true : false; // Next openscad releases after 2015.03.xx will have support angle parameter
  // Using angle parameter when possible provides huge speed boost, avoids a difference operation

  //echo(R);
  render(convexity=5)
  if (angleSupport) {
    rotate([0,0,-angle/2]) rotate_extrude(angle=angle,convexity=3) {
      difference() {
        if (R<=0) {
          mirror([1,0]) translate([R-r, 0, 0]) fil_2d_i(r,90,extendX,extendY, halfAlign, r2);
        } else {
          translate([R-r, 0, 0]) fil_2d_i(r,90,extendX,extendY, halfAlign, r2);
        }
        if (R-r < 0)
          translate([-4*(r+extendX),-1]) square([4*(r+extendX),r+extendY+2]);
      }
    }
  } else {
    difference() {
      rotate_extrude(convexity=7) {
        difference() {
          if (R<=0) {
            mirror([1,0]) translate([R-r, 0, 0]) fil_2d_i(r,90,extendX,extendY, halfAlign, r2);
          } else {
            translate([R-r, 0, 0]) fil_2d_i(r,90,extendX,extendY, halfAlign, r2);
          }
          if (R-r < 0)
            translate([-4*(r+extendX),-1]) square([4*(r+extendX),r+extendY+2]);
        }
      }
      angle_cut(angle);
    }
  }
}

// 3d linear inside fillet.
module fil_linear_i(l, r, angle=90,extendX=0, extendY=0, halfAlign=false, r2=0) {
  rotate([0, -90, 180]) {
    linear_extrude(height=l, center=false) {
      fil_2d_i(r, angle,extendX,extendY, halfAlign, r2);
    }
  }
}

```


[User]
I'd like to be able to create a zentangle bracelet. I'm looking to create a design similar to the one shown in the attached photo.

The design should be based on your "Symmetrical triangle generator" but modified to be able to wrap around a cylinder. In essence, I want to be able to take a flat, rectangular pattern and seamlessly transform it into a cylindrical bracelet.

The bracelet should have customizable parameters for:

*   **radius:** The radius of the bracelet.
*   **height:** The height (or width) of the bracelet.
*   **line\_width:** The width of the lines in the zentangle pattern.
*   **thickness:** The thickness of the bracelet.
*   **fn:** The \$fn parameter to control the smoothness of the cylinder.

The zentangle pattern itself should be composed of a series of symmetrical virtual triangles, as in your original design. The number of triangles in the x and y directions should be automatically calculated based on the width and length of the bracelet, but I'd like it to generally follow a ratio of 0.2 triangles per unit of width and 0.075 triangles per unit of length.

The core idea is to generate the zentangle pattern on a flat rectangle, then use some kind of transformation to "roll" it into a cylinder. The pattern should be subtracted from the cylinder, leaving the design as negative space.

Could you help me create an OpenSCAD design that accomplishes this? I'd also need the code for the "Symmetrical Triangle Generator" as well, since it seems to be used as a base for this design. Also, if you use any external libraries in your response, please specify which ones.

[Assistant]
zentangle_bracelet.scad:
```
radius = 25;
height = 30;
line_width = 1.25;
thickness = 2;
fn = 24;

//////////////
// 2D Drawing
//

// Draws a line between the points.
//
// Parameters:
//     point1 - the start point [x1, y1] of the line.
//     point2 - the end point [x2, y2] of the line.
//     width  - the line width.
//     cap_round - ends the line with round decorations that has a radius equal to half of the width of the line.
module line(point1, point2, width = 1, cap_round = true) {
    angle = 90 - atan((point2[1] - point1[1]) / (point2[0] - point1[0]));
    offset_x = 0.5 * width * cos(angle);
    offset_y = 0.5 * width * sin(angle);

    offset1 = [-offset_x, offset_y];
    offset2 = [offset_x, -offset_y];

    if(cap_round) {
        translate(point1) circle(d = width, $fn = 24);
        translate(point2) circle(d = width, $fn = 24);
    }

    polygon(points=[
        point1 + offset1, point2 + offset1,
        point2 + offset2, point1 + offset2
    ]);
}

// Creates a polyline, defined by the vector of the segment points.
//
// Parameters:
//     points - the coordinates of the polyline segments.
//     width  - the line width.
module polyline(points, width = 1, index = 0) {
    if(index < len(points)) {
        if(index == 0) {
            polyline(points, width, index + 1);
        } else {
            line(points[index - 1], points[index], width);
            polyline(points, width, index + 1);
        }
    }
}

///////////////////
// Turtle Graphics
//

// Creates a vector containing the current point [x, y] and the angle of the turtle.
// Parameters:
//     x - the x coordinate of the turtle.
//     y - the y coordinate of the turtle.
//     angle - the angle of the turtle.
// Return:
//     the turtle vector [[x, y], angle].
function turtle(x, y, angle) = [[x, y], angle];

// Moves the turtle forward the specified distanc
// Parameters:
//     turtle - the turtle vector [[x, y], angle].
// Return:
//     the new turtle vector after forwarding
function forward(turtle, length) =
    turtle(
        turtle[0][0] + length * cos(turtle[1]),
        turtle[0][1] + length * sin(turtle[1]),
        turtle[1]
    );

// Returns a new turtle vector with the given point.
// Parameters:
//     turtle - the turtle vector [[x, y], angle].
//     point - the new point of the turtle.
// Return:
//     the new turtle vector
function set_point(turtle, point) = [point, turtle[1]];

// Returns a new turtle vector with the given angle.
// Parameters:
//     turtle - the turtle vector [[x, y], angle].
//     angle - the angle of the turtle.
// Return:
//     the new turtle vector
function set_angle(turtle, angle) = [turtle[0], angle];

// Turns the turtle the specified number of degrees.
// Parameters:
//     turtle - the turtle vector [[x, y], angle].
//     angle - number of degrees.
// Return:
//     the new turtle vector
function turn(turtle, angle) = [turtle[0], turtle[1] + angle];

///////////////////
// Turtle Spirally
//

// Moves the turtle spirally. The turtle forwards the 'length' distance, turns 'angle' degrees, minus the length with 'step' and then continue next  spiral until the 'min_length' is reached.
// Parameters:
//     turtle - the turtle vector [[x, y], angle].
//     length - the beginning length.
//     decreasing_step - the next length will be minus with the decreasing_step.
//     angle - the turned degrees after forwarding.
//     ending_length - the minimum length of the spiral.
module spiral(turtle, length, decreasing_step, angle, ending_length = 10, line_width = 1) {
    if(length > ending_length) {
        turtle_after_forwarded = forward(turtle, length);
        line(turtle[0], turtle_after_forwarded[0], line_width);
        turtle_after_turned = turn(turtle_after_forwarded, angle);
        spiral(turtle_after_turned, length - decreasing_step, decreasing_step, angle, ending_length, line_width);
    }
}

////////////////////////////////
// Symmetrical virtual triangle

// Use the given points, draw a ployline. Repeat the previous step after rotate 120 and 240 degrees.
// Parameters:
//     points - the coordinates of the polyline segments.
//     line_width  - the line width.
module virtual_triangle(points, line_width = 1) {
    polyline(points, line_width);
    rotate([0, 0, 120]) polyline(points, line_width);
    rotate([0, 0, 240]) polyline(points, line_width);
}

// Draw a symmetrical virtual triangle.
// Parameters:
//     points - the coordinates of the polyline segments of a single virtual_triangle.
//     length - the length of a triangle side.
//     x_tris - the numbers of triangles in the x directions
//     y_tris - the numbers of triangles in the y directions
//     line_width  - the line width.
module symmetrical_virtual_triangle(points, length, x_tris, y_tris, line_width = 1) {
    height = length * sqrt(3) / 2;
    x_numbers = x_tris % 2 == 0 ? x_tris + 1 : x_tris;
    y_numbers = y_tris - 1; //(y_tris % 2 == 0 ? y_tris + 1 : y_tris) - 1;
    for(y_factor = [0 : y_numbers]) {
        for(x_factor = [0 : x_numbers]) {
            x_offset = length / 2 * x_factor + (y_factor % 2) * length / 2;
            y_offset = height * y_factor;

            if(x_factor % 2 == 0) {
                if(x_factor != 0 || y_factor % 2 != 0) {
                    translate([x_offset, y_offset, 0])
                        virtual_triangle(points, line_width);
                }
            } else {
                if(x_factor != x_numbers || y_factor % 2 == 0) {
                    translate([x_offset, height / 3 + y_offset, 0])
                    mirror([0, 1, 0])
                        virtual_triangle(points, line_width);
                }
            }
        }
    }
}

/* Examples
points1 = [
    [17.5, -10],
    [9.5, -10],
    [5, -2.5],
    [1.5, -2.5],
    [0, 0],
    [-1.5, -2.5],
    [-5, -2.5],
    [-9.5, -10],
    [-17.5, -10]
];

linear_extrude(2) symmetrical_virtual_triangle(points1, 35, 10, 4, 1);

points2 = [
    [10, -6],
    [-6.5, -6],
    [-3, 0],
    [0, 0]
];

linear_extrude(2) translate([225, 0, 0]) symmetrical_virtual_triangle(points2, 20, 10, 4, 0.5);

points3 = [
    [0, 0],
    [1.5, 2.5],
    [1.5, -6],
    [-4, -6],
    [-6.5, 0]
];

linear_extrude(2) translate([0, 200, 0]) symmetrical_virtual_triangle(points3, 20, 10, 4, 0.5);
*/

//////////////
// String API
//

// Returns a new string that is a substring of this string. The substring begins at the specified `begin` and extends to the character at index `end` - 1. Thus the length of the substring is `end` - `begin`.
// Parameters:
//     begin - the beginning index, inclusive.
//     end - the ending index, exclusive.
// Returns:
//     The resulting string.
function sub_string(string, begin, end, result = "") =
    end == undef ? sub_string(string, begin, len(string)) : (
        begin == end ? result : sub_string(string, begin + 1, end, str(result, string[begin]))
    );

// Splits this string around matches of the given delimiting character.
// Parameters:
//     string - the source string.
//     delimiter - the delimiting character.
function split(string, delimiter) =
        len(search(delimiter, string)) == 0 ? [string] : split_string_by(search(delimiter, string, 0)[0], string);

function split_string_by(indexes, string, strings = [], i = -1) =
    i == -1 ? split_string_by(indexes, string, [sub_string(string, 0, indexes[0])], i + 1) : (
        i == len(indexes) - 1 ? concat(strings, sub_string(string, indexes[i] + 1)) :
                split_string_by(indexes, string, concat(strings, sub_string(string, indexes[i] + 1, indexes[i + 1])), i + 1)
    );

// Parse string to number
// Parameters:
//     string - the source string.
// Results:
//     The resulting number.
function parse_number(string) = string[0] == "-" ? -parse_positive_number(sub_string(string, 1, len(string))) : parse_positive_number(string);

function str_num_to_int(num_str, index = 0, mapper = [["0", 0], ["1", 1], ["2", 2], ["3", 3], ["4", 4], ["5", 5], ["6", 6], ["7", 7], ["8", 8], ["9", 9]]) =
    index == len(mapper) ? -1 : (
        mapper[index][0] == num_str ? mapper[index][1] : str_num_to_int(num_str, index + 1)
    );

function parse_positive_int(string, value = 0, index = 0) =
    index == len(string) ? value : parse_positive_int(string, value * pow(10, index) + str_num_to_int(string[index]), index + 1);

function parse_positive_decimal(string, value = 0, index = 0) =
    index == len(string) ? value : parse_positive_decimal(string, value + str_num_to_int(string[index]) * pow(10, -(index + 1)), index + 1);

function parse_positive_number(string) =
    len(search(".", string)) == 0 ? parse_positive_int(string) :
        parse_positive_int(split(string, ".")[0]) + parse_positive_decimal(split(string, ".")[1]);

// for MakerBot Customizer
function strs_to_points(xs, ys, points = [], index = 0) =
    index == len(xs) ? points : strs_to_points(xs, ys, concat(points, [[parse_number(xs[index]), parse_number(ys[index])]]), index + 1);

// ==

// Create a triangle which is 1/fn of a circle.
// Parameters:
//     r  - the circle radius
//     fn - the same meaning as the $fn of OpenSCAD
module one_over_fn_for_circle(r, fn) {
    a = 360 / fn;
	x = r * cos(a / 2);
	y = r * sin(a / 2);
	polygon(points=[[0, 0], [x, y],[x, -y]]);
}

// Transform a model inito a cylinder.
// Parameters:
//     length - the model's length
//     width  - the model's width
//     square_thickness - the model's thickness
//     fn - the same meaning as the $fn of OpenSCAD
module square_to_cylinder(length, width, square_thickness, fn) {
    r = length / 6.28318;
    a = 360 / fn;
	y = r * sin(a / 2);
	for(i = [0 : fn - 1]) {
	    rotate(a * i) translate([0, -(2 * y * i + y), 0]) intersection() {
		    translate([0, 2 * y * i + y, 0])
		        linear_extrude(width)
				    one_over_fn_for_circle(r, fn);
			translate([r - square_thickness, 0, width])
	            rotate([0, 90, 0])
	                children(0);
		}
	}
}

module zentangle(width, length, line_width, thickness) {
	xs = "-8.75.5 -4.75 -2.5 -0.75 0 0.75 2.5 4.75 8.75";
	ys = "-5 -5 -1.5 -2.5 0 -2.5 -1.5 -5 -5";
	triangle_side_length = 17.5;
	x_triangles = 0.2 * width;
	y_triangles = 0.075 * length;

	linear_extrude(thickness) union() {
		intersection() {
			square([width, length]);
			translate([-triangle_side_length / 2.75, 0, 0]) symmetrical_virtual_triangle(strs_to_points(split(xs, " "), split(ys, " ")), triangle_side_length, x_triangles, y_triangles, line_width);
		}

		difference() {
			square([width, length]);
			offset(delta = -line_width * 2) square([width, length]);
		}
	}
}

module zentangle_bracelet(radius, height, line_width, thickness, fn) {
    length = 6.28318 * radius;
	width  = height;
	square_to_cylinder(length + line_width * 2,  width, 2, fn)
		zentangle(width, length, line_width, thickness);
}

zentangle_bracelet(radius, height, line_width, thickness, fn);

// zentangle(height, 6.28318 * radius, line_width, thickness);

```


[User]
Okay, I'm looking for a parametric OpenSCAD design for a nozzle storage case. I've seen some good ones, but they don't quite fit my needs, so I'd like one custom-built. I want to be able to specify the number of nozzles in both the width and length, and also the spacing between them. The case will have a hinged lid.

Here are the parameters I'm thinking of. I'd like these to all be adjustable via the Customizer:

**Nozzle Settings**

*   `nozzleBaseHeight`: Height of the nozzle's threaded part.
*   `nozzleTipHeight`: Height of the nozzle's tip part.
*   `nozzleBaseDia`: Diameter of the nozzle's threaded part.
*   `width_number`: Number of nozzles along the case's width.
*   `length_number`: Number of nozzles along the case's length.
*   `widthDistance`: Distance between nozzles and edges along the case's width.
*   `lengthDistance`: Distance between nozzles and edges along the case's length.
*   `inaccuracy`: A general inaccuracy value for nozzle holes; should increase the hole size a bit to make sure nozzles fit. This should be *added* to `nozzleBaseDia` for the hole diameter.

**Dimensions**

*   `interiorFillet`: Radius of the case's interior fillets.
*   `hingeWidth`: Width of the hinge. This should have a maximum value equal to the interior width.

**Walls**

*   `coverThickness`: Thickness of the top and bottom walls.
*   `sidewallWidth`: Thickness of the case's side walls.
*   `lidInsetHeight`: Amount the lid protrudes into the case.
*   `hingeThickness`: Thickness of the hinge (should be very thin to keep it flexible).
*   `hingeLengthScale`: Multiplier to adjust the hinge's length, based on the case's height.

**Derived/Calculated Dimensions**

*   `interiorWidth`: Interior width of the case, calculated from nozzle count, diameter, and spacing, plus wall thickness.
*   `interiorLength`: Interior length of the case, calculated similarly.
*   `interiorHeight`: Interior height of the case.

**Details**

*  `rimInset`: How far the top and bottom extend beyond the sides of the case.
*  `tabSize`: Length of a tab on the lid. This should be optional and removable if set to zero.
*  `hingeFillet`: Fillet radius for the hinge and tab.

**Label Settings**

*  `lblToggle`:  A toggle (1 for on, 0 for off) to control if text labels are displayed.
*  `lblSize`: Size of the labels.
*  `lblHeight`: Height of the labels
*  `lblText`:  A list of strings representing the labels. The number of entries in this list should match `length_number`.

**Printer Tolerances**
* `lidInsetOffset`: Adjusts the tightness of the case when closed.

The `nozzleBaseDia_ina` variable will be calculated as `nozzleBaseDia + inaccuracy`.  The `$fn` variable should be set to 120 for resolution, and an `eps = 0.1` should be used as a small epsilon value for calculations to avoid errors.

For the main case construction, I'd like to use a module called `rrect` which creates a rounded rectangle given a height, width, length, and radius. There should also be a `rrectTube` module which creates a rounded rectangle tube by subtracting an inner rectangle from the outer. The case should be built up using these rounded rectangles.

The text labels should be on the top of the base section. These should be extruded. Lines should also be drawn next to the text and across the nozzle hole rows to clearly label each row. The text should be rotated to make it easier to read in the top-down view.

The lid should have a small inset which fits inside the base for a snug fit, and also a tab to make it easier to open.

I hope this is clear! Let me know if you have any questions.

[Assistant]
customizable_nozzle_case.scad:
```
/*[Nozzle Settings]*/

// Height of the threaded part of the nozzle [mm]
nozzleBaseHeight = 9;

// Height of the tip part of the nozzle [mm]
nozzleTipHeight = 4;

// Diameter of the threaded part of the nozzle [mm]
nozzleBaseDia = 6;

// Quantity of nozzles in X-direction
width_number = 5;//[2:10]

// Quantity of nozzles in Y-direction (see lblText if changed)
length_number = 4;//[2:10]

// Distance between and at the edges of the nozzleholes in X-direction [mm]
widthDistance = 5;
// Distance between and at the edges of the nozzleholes in Y-direction [mm]
lengthDistance = 5;

// General inaccuracy for the nozzleholes. Reduce to get a tighter fit [mm]
inaccuracy = 0.3;

nozzleBaseDia_ina = nozzleBaseDia + inaccuracy;

/*[Dimensions]*/

// Case interior fillet radius [mm]
interiorFillet = 2.0;

// Width of the hinge [mm]
hingeWidth = width_number * nozzleBaseDia_ina + (width_number+1) * widthDistance - 10;

/*[Walls]*/

// Horizontal wall (top and bottom) thickness [mm]
coverThickness = 1.0;

// Vertical wall (side) thickness [mm]
sidewallWidth = 1.2;

// Amount the lid protrudes into the case (larger value allows the case to close more securely) [mm]
lidInsetHeight = 1.2;

// Thickness of the hinge (it should be no more than a few layers thick keep it flexible) [mm]
hingeThickness = 0.4;

// hinge length multiplier (as a function of case height - longer hinges may be needed for less flexible plastics)
hingeLengthScale = 1.1;

// Width of the case in mm (interior dimension)
interiorWidth = width_number * nozzleBaseDia_ina + (width_number+1) * widthDistance + sidewallWidth;

// Length of the case in mm (interior dimension)
interiorLength = length_number * nozzleBaseDia_ina + (length_number+1) * lengthDistance + sidewallWidth;

// Height of the case in mm (interior dimension)
interiorHeight = nozzleBaseHeight + nozzleTipHeight + 0.6;

/*[Details]*/

// Distance the top and bottom surfaces extend beyond the sides of the case (makes the case easier to open) [mm]
rimInset = 0.6;

// Length of the opening tab on the lid of the case (optional - set to 0 to remove)
tabSize = 1;

// Fillet radius used for hinge and tab
hingeFillet = 3;

/*[Label Settings]*/ // To change the text you have to open this file in OpenSCAD
// Toggle text, 1 is on
lblToggle = 1; //[1:True, 0:False]

// Size of the labels
lblSize = 3;

// Height of the labels [mm]
lblHeight = 1.0;

// Labeltext - At the moment it is only possible to write words with 5 characters, all longer  words going into the lines. The amount of elements should be equals the length_number.
lblText = [
           "0.2mm",
           "0.3mm",
           "0.4mm",
           "0.5mm"
        ];

/*[Printer Tolerances]*/

// Adjust the tightness of the closed case (larger value makes the case looser, negative value makes it tighter - try adjusting in 0.1mm increments)
lidInsetOffset = 0.1;

/*[hidden]*/

$fn = 120; // resolution

eps = 0.1;

module case()
{
	// minimal error checking
	hingeWidth = min(hingeWidth, interiorWidth);
	hingeThickness = min(hingeThickness, coverThickness);
	lidInsetHeight = min(lidInsetHeight, interiorHeight);

	baseLength = interiorLength + sidewallWidth*2;
	baseWidth = interiorWidth + sidewallWidth*2;
	baseRadius = interiorFillet + sidewallWidth;

	caseLength = baseLength + rimInset*2;
	caseWidth = baseWidth + rimInset*2;
	caseRadius = baseRadius + rimInset;

	hingeLength = hingeLengthScale * interiorHeight + coverThickness*2;
	centerY = (caseLength + hingeLength)/2;

	filletXOffset = hingeWidth/2 + hingeFillet;
	filletYOffset = hingeLength/2 - hingeFillet;

	module rrect(h, w, l, r) {
		r = min(r, min(w/2, l/2));
		w = max(w, eps);
		l = max(l, eps);
		h = max(h, eps);
		if (r <= 0) {
			translate([-w/2, -l/2,0]) {
				cube([w,l,h]);
			}
		} else {
			hull() {
				for (y = [-l/2+r, l/2-r]) {
					for (x = [-w/2+r, w/2-r]) {
						translate([x,y,0]) {
							cylinder(h=h, r=r, center=false);
						}
					}
				}
			}
		}
	}

	module rrectTube(h, ow, ol, or, t) {
		difference() {
			rrect(h=h, w=ow, l=ol, r=or);
			translate([0,0,-eps]) {
				rrect(h=h+eps*2, w=ow-t*2, l=ol-t*2, r=or-t);
			}
		}
	}

	union() {
		// bottom surfaces
		for (i = [-centerY, centerY]) {
			translate([0,i,0]) {
				rrect(h=coverThickness, w=caseWidth, l=caseLength, r=caseRadius);
			}
		}

		translate([0,0,coverThickness-eps]) {

            // base
			translate([0,centerY,0]) {
				rrectTube(h=nozzleBaseHeight+eps, ow=baseWidth, ol=baseLength, or=baseRadius, t=sidewallWidth);

            //lid
                translate([0,0,nozzleBaseHeight])
                rrectTube(h=lidInsetHeight+eps, ow=interiorWidth - lidInsetOffset, ol=interiorLength - lidInsetOffset, or=interiorFillet - lidInsetOffset/2, t=sidewallWidth);

			// nozzlecase
                difference() {
                    rrect(h=nozzleBaseHeight, w=baseWidth, l=baseLength, r=baseRadius);

                    nozzle();

                    if (lblToggle == 1)
                    {
                        maketext();
                    }

                }
			}

			translate([0,-centerY,0]) {

             // lid
                rrectTube(h=nozzleTipHeight+eps, ow=baseWidth, ol=baseLength, or=baseRadius, t=sidewallWidth);
			}
		}

		// hinge
		if (hingeWidth > caseWidth - caseRadius*2) {
			translate([-hingeWidth/2,-centerY,0]) {
				cube([hingeWidth, centerY*2, hingeThickness]);
			}
		} else {
			difference() {
				translate([-hingeWidth/2 - hingeFillet,-centerY,0]) {
					cube([hingeWidth + hingeFillet*2, centerY*2, hingeThickness]);
				}

				// fillet hinge
				for (x = [-filletXOffset, filletXOffset]) {
					hull() {
						for (y = [-filletYOffset, filletYOffset]) {
							translate([x,y,-eps]) {
								cylinder(h=hingeThickness + eps*2, r=hingeFillet, center=false);
							}
						}
					}
				}
			}
		}

		// tab
		if (tabSize > 0) {
			hull() {
				for (x = [hingeFillet - hingeWidth/2, hingeWidth/2 - hingeFillet]) {
					translate([x,-caseLength - hingeLength/2 - tabSize + hingeFillet,0]) {
						cylinder(h=coverThickness, r=hingeFillet, center=false);
					}
				}
				translate([-hingeWidth/2,-centerY,0]) {
					cube([hingeWidth, eps, coverThickness]);
				}
			}
		}
	}

    module maketext()
    {
        for (n = [0:length_number-1]){

            translate([0,(n+1)*lengthDistance+ n*nozzleBaseDia_ina-caseLength/2,nozzleBaseHeight-lblHeight]) {
                // text
                linear_extrude(height = lblHeight) {
                    rotate([0,0,180])
                    text(lblText[n], size = lblSize, valign = "center", halign = "center", spacing = 1.2);
                }

                // Lines
                translate([8,0,0])
                    cube([hingeWidth / 2 - widthDistance-1,0.6,lblHeight]);
                translate([hingeWidth / 2 - widthDistance+2+4.4,0, 0])
                    cube([0.6,nozzleBaseDia/2,lblHeight]);

                mirror()
                {
                    translate([8,0,0])
                        cube([hingeWidth / 2 - widthDistance-1,0.6,lblHeight]);
                    translate([hingeWidth / 2 - widthDistance+2+4.4,0, 0])
                        cube([0.6,nozzleBaseDia/2,lblHeight]);
                }

            }
        }
    }
}

module nozzle(x, y, z)
{
    translate([nozzleBaseDia_ina/2 - (width_number/2)*nozzleBaseDia_ina - ((width_number-1)/2)*widthDistance, nozzleBaseDia_ina/2 - (length_number/2)*nozzleBaseDia_ina - ((length_number-1)/2)*lengthDistance, 0])
    {
    for(n = [0 : width_number - 1])
    {
        for(m = [0 : length_number - 1])
        {
            translate([n * (nozzleBaseDia_ina + widthDistance), m * (nozzleBaseDia_ina + lengthDistance),0])
            {
                cylinder(d = nozzleBaseDia_ina, h = nozzleBaseHeight);
            }
        }
    }
}
}

case();

// preview[view:north, tilt:top]
```


[User]
Hi there! I'm looking to create a parametric pen design in OpenSCAD, similar to the one I made previously on Thingiverse but with some improvements and using libraries. I'm aiming for a design that's easy to print, doesn't require supports, and has a nice, functional clip, plus a cap that fits tightly and won't rotate.

Here's what I'm thinking:

**Overall Shape and Features:**
*   The pen body should have a square cross-section, defined by a `pen_width` parameter. This width should default to 10 but be adjustable.
*   The pen will have two main parts: an upper and a lower portion, joined by a threaded connection that's very tight.
*   The pen needs to house a standard pen refill. I'll specify the exact dimensions below.
*   The end of the pen should come to a point. I'm thinking a simple pyramid shape made from 4 triangles.
*   There will be a clip on one side of the pen body, designed to hold it to a pocket or notebook.
*   I also want the ability to add a text label on one side of the pen body using the `text()` module in openscad, and would like for the size and depth of that text to be adjustable, with default values.

**Specific Dimensions:**
*   **Pen Refill:** I'll use standard pen refill dimensions:
    *   A cylinder with diameter 3.1 and height 3.6
    *   Then, a cylinder of diameter 4, length 6.5-3.6
    *   Then, a cylinder of diameter 4, length 23.5-6.5
    *   Then a cylinder of diameter 6.4 length 98.4-23.5-7
     * And a cap with a cylinder with length 7, d1=5.8, d2=5.8 (not a cone)

*   **Text Label:**
    *   The `letter_size` should default to 6.
    *   The `letter_height` should default to 0.5.
    *   The `font` can default to "Arial" but should be changeable.
    *   The text to be printed will be a string parameter, with a default value of "www.thingiverse.com".
*   **Point:** The point at the end of the pen should be a pyramid defined by a four-sided base and apex. The height of the point should match the `pen_width`.
*   **Clip:** The clip should have an interesting shape and be firmly attached. I would like to see some kind of cut-out to make the clip more functional.  The clip should be placed at the top of the pen body, along one of the square edges.
*  **Threads:** The threads for the connection between the upper and lower body should use a standard thread, the size of which should be modifiable using a diameter parameter `d`. The threads should be short but very tight.

**Libraries:**
*   I'd like to use the `geo.otf` font library for the font.

**Modules:**

I'm imagining the design would be broken into several modules such as:
*   `PenRefill()`: creates the pen refill shape.
*   `letter(l)`: Creates a single letter of text, and the `letter_height` parameter determines how much the letter is extruded.
*   `EndPoint()`: Creates the pointed end of the pen using the pyramid module.
*   `Pen()`: creates the main body of the pen, including the cavity for the refill, the point at the end, and the text label. It should be a difference of a solid cube and then the other shapes (refill, cut end, etc) are subtracted from it.
*   `Clip()`: create the pen clip, including a section which is cut out of the clip for function.
*   `ThreadedConnection(d)`: creates the threaded connection between the upper and lower bodies, taking the desired thread diameter as a parameter.
*  `CutTemplate(d)`: creates a cutting template which removes material from the main pen body to create the threaded section. This should be very short.
*   `VeryTipCut()`: removes a small amount of material from the very tip of the pen so the user can easily attach a "very tip".
*   `LowerPart(d)`: creates the lower part of the pen, using the Pen(), CutTemplate(d) and VeryTipCut() modules.
*    `LowerPartD(d)`: creates the lower part of the pen but can also be used in the upper part of the pen, this version has a cylindrical cut at the top of it.
*   `UpperPart()`: creates the upper part of the pen, using the Pen(), LowerPartD(), and VeryTipCut() modules.
*   `AssemblyPlate()`: creates the assembled pen.

Let me know if you have any questions, or if you need more details. I am excited to see what you come up with!

[Assistant]
parker_v2.scad:
```
use <geo.otf>

//Text to be printed on the pen
pen_text="www.thingiverse.com";

//Font for the label. You can try "Geo" for more square look.
font = "Arial";

//Size of the text
letter_size = 6;
//Depth of the text
letter_height = .5;

//Width of the pen. Should not be less than 10.
pen_width=10;

module PenRefill()
{
    fn=20;
    h1=3.6;
    h2=6.5;
    h3=23.5;
    h4=98.4;
    ht=7;
    color("silver")
    cylinder(d=3.1, h=h1, $fn=fn);
    translate([0,0,h1])cylinder(d=/*2.54*/4, h=h2-h1, $fn=fn);
    color("silver")
    translate([0,0,h2])cylinder(d=/*2.4*/4, h=h3-h2, $fn=fn);
    color("silver")
    translate([0,0,h3+ht])cylinder(d=6.4, h=h4-h3-ht, $fn=fn);

    translate([0,0,h3])
    cylinder(h = ht, d1 = /*4*/5.8, d2 = 5.8, center = false, $fn=fn);
}

module letter(l) {
  translate([0,0,-letter_height / 2])
  {
    linear_extrude(height = letter_height, convexity = 10) {

        text(l, size = letter_size, font = font, halign = "center", valign = "center", $fn = 16, spacing=1);
    }
  }
}

module EndPoint()
{
    endh = pen_width;
    translate([0,0,endh-3])
    mirror([0,0,1])
    polyhedron(
      points=[ [pen_width,pen_width,0],[pen_width,-pen_width,0],[-pen_width,-pen_width,0],[-pen_width,pen_width,0], // the four points at base
               [0,0,endh]],                                 // the apex point
      faces=[[0,1,4],[1,2,4],[2,3,4],[3,0,4],               // each triangle side
                  [1,0,3],[2,1,3] ]                         // two triangles for square base
     );
}

module Pen()
{
    //render()
    difference()
    {
        difference()
        {
            translate([0,0,50])scale([pen_width,pen_width,120])cube(1, center=true);
            translate([0,0,-5])PenRefill();
        }
        // Cut the end
        difference()
        {
            scale([pen_width*2,pen_width*2,pen_width])cube(1, center=true);
            EndPoint();
        }

        translate([0,0,-pen_width/2-2]) // Dirty fix, I'm to lazy to write clear code
        cube(pen_width, center=true);

    }
    Clip();
    rotate([0,0,-90]) // The side opposite to the clip
    translate([pen_width/2+letter_height/2,0,50])rotate([0,90,0])letter(pen_text);

}

module Clip()
{
    difference()
    {
        translate([0,0,70])
        {
            translate([-pen_width/2,pen_width/2+2,0])
            scale([pen_width,4,40])cube(1);
            translate([-pen_width/2,pen_width/2,36])
            scale([pen_width,4,4])cube(1);
        }

        translate([0,pen_width,70+pen_width/sqrt(2)])
        {
            difference()
            {
                translate([0,0,-pen_width*sqrt(2)/4-.1])
                scale([pen_width*sqrt(2),pen_width,pen_width*sqrt(2)/2])
                cube(1, center=true);

                rotate([0,45,0])
                cube(pen_width, center=true);
            }

        }
    }
}

module ThreadedConnection(d)
{
    radius = (pen_width-d)/2-1;
    cylinder(h=10, r=radius, $fn=50);
    translate([0,0,2])scale([radius+.2,radius+.2,2]) sphere(1, $fn=30);
    translate([0,0,5])scale([radius+.2,radius+.2,2]) sphere(1, $fn=30);
}

module CutTemplate(d)
{
    color("red")
    translate([0,0,95])
    {
        translate([0,0,6.5])
        translate([0,0,-3])
        translate([0,0,25])
        scale([pen_width*2,pen_width*2,50])cube(1.1, center=true);
        translate([0,0,-8])
        ThreadedConnection(d);

    }
    color("red")
    Clip();
}

module VeryTipCut()
{
    translate([0,0,-3.0])
    scale([30,30,4])cube(1, center=true);
}

module LowerPart(d)
{
    LowerPartD(0);
}

module LowerPartD(d)
{
    //render()
    difference()
    {
        Pen();
        CutTemplate(d);
        VeryTipCut();
        rotate([0,0,-45])
        translate([0,pen_width/2-1,86+1])
        cylinder(h=10.1, d=2+d, $fn=32);
    }
}

module UpperPart()
{
    //render()
    difference()
    {
        Pen();
        LowerPartD(.2);
        VeryTipCut();
    }

}

module AssemblyPlate()
{
    translate([0,0,96])
    rotate([0,0,180])
    rotate([180,0,0])
    LowerPart();

    translate([pen_width+5,0,110])
    rotate([180,0,0])
    UpperPart();
}

//Pen();
/*UpperPart();
CutTemplate();*/
//LowerPart();
AssemblyPlate();

```


[User]
I have a design concept for a 3D printer calibration tool that I'd like your help in creating an OpenSCAD model for. The purpose of this tool is to test and calibrate a 3D printer's accuracy when printing walls, especially for parts that need to fit together precisely.

The basic idea is to create a test piece with several "strips" that are designed to test how much a printer overshoots when printing walls. The main part of the test piece will be a rectangular block (40mm long, 3.2mm tall). We'll need to be able to adjust the number of these test strips (let's say between 1 and 4), with spacing of 10mm between each strip. We need to be able to adjust the height of the strips, probably starting at 3.2mm and going to 6.4mm.

The strips themselves are where it gets a little tricky. They need to be tapered along their length, with a very slight slope of about 1 in 100. We'll do this by using a `polygon()` function, and offsetting the points by multiples of a variable `i`, which will start at 0.1mm. This will allow us to adjust the wall thickness by very small increments to test our printer's accuracy.

Each test strip will be created using a `linear_extrude` of a polygon. We'll use a `difference()` operation to cut these tapered shapes out of the main block. We also want a little undercut at the base of each strip, about 0.2mm wide and 0.4mm tall, to help with measurements.

In addition to the main block with cutouts, I'd also like to have a set of matching "positive" test strips on the side. These will be created in a similar way, using `linear_extrude` of a polygon, but instead of being cut out, they'll be added to the side of the block. These will be like the inverse of the first set of strips, and will help us test how parts fit together. We'll need to be able to control the spacing of the strips, and how much they're offset from the main block.

Could you generate a parametric OpenSCAD file that implements this design? We shouldn't need any external libraries for this, just the built-in OpenSCAD features. Let me know if you need any more details!

[Assistant]
wall_thickness.scad:
```
// Number of test strips to print (for averaging)
strips = 4; // [1:4]

// Height of the strips
height = 3.2; // [3.2, 6.4]

/* [hidden] */

a = 40; // Block length
b = 10; // Block spacings
d = a/25; // Taper amount (1 in 100 slope, divided by 4 surfaces)
e = 0.2; // Undercut width
f = 0.4; // Undercut height
g = b; // cutout centering
h = b; // Cutout width, roughly
i = 0.1; // Test strip increments

difference () {
    cube([a,b*(strips*2 + 1),height]);
    for (x=[0:strips-1]) {
        wedge = [[0,0],[0,b],[a,b+d],[a,0],[0,0]];
        adjusted_wedge = wedge + [[0,-i*x],[0,i*x],[0,i*x],[0,-i*x],[0,-i*x]];
        undercut_wedge = adjusted_wedge + [[0,-e],[0,e],[0,e],[0,-e],[0,-e]];
        translate([0,(2*x + 1)*b,height/4]) {
            linear_extrude(height=f) {
                polygon(undercut_wedge);
            };
            linear_extrude(height=height) {
                polygon(adjusted_wedge);
            };
        };
    };
}

for (x=[0:strips - 1]) {
    wedge = [[0,0],[0,b],[a,b],[a,-d],[0,0]];
    adjusted_wedge = wedge + [[0,-i*x],[0,i*x],[0,i*x],[0,-i*x],[0,-i*x]];
    translate ([a+10,(1 + 2*x)*b,0]) linear_extrude(height=height) polygon(adjusted_wedge);
}

```


[User]
I'm looking for an OpenSCAD design for a specialized linear bearing. It needs to be pretty different from a standard bearing. Instead of using ball bearings, I want it to use a series of spring-loaded arms. These arms will help with leveling and will provide some cushioning.

Here's a breakdown of what I have in mind:

*   **Overall Shape:** The bearing should be cylindrical, designed to slide along a rod or pipe.
*   **Spring-Loaded Arms:** Instead of traditional ball bearings, the bearing will have a set of evenly spaced arms around the inner circumference. These arms should be springy and push inward, towards the center, to maintain contact with the rod. Ideally, these springs would have a slight twist to them as well to facilitate movement.
*   **Dimensions:** I need the design to be parametric so I can adjust the following:
    *   **Outer Diameter (OD):** The external diameter of the bearing.
    *   **Inner Diameter (ID):** The diameter of the rod the bearing will slide on.
    *   **Length:** The total length of the bearing.
*   **Mounting Grooves (Optional):**
    *   It would be great if the design could optionally include grooves on the outer surface for mounting.
    *   I should be able to specify the depth of the grooves and how far in they are from the ends of the bearing.
    *   If these values are set to 0 or less, the grooves should be omitted.
*   **Spring Properties:**
    *   **Thickness:** I need to be able to adjust the thickness of the spring arms. This will impact the stiffness of the bearing. Something in the range of 1.0 to 1.3 would be a good starting point.
    *   **Number of Springs:** The number of spring arms around the inner circumference should be adjustable.
    *   **Spring Twist Angle:** Each spring should have a slight twist, and I want to be able to control the angle of this twist.
*   **Chamfered Ends:** The bearing should have chamfered (beveled) edges at both ends. The size of the chamfer should be adjustable.
*   **Nubs:**  At the end of each spring arm, near the contact point with the rod, there should be a small, rounded nub. This will help to reduce friction and wear. These nubs should extend into the chamfer.

**High-Resolution Option:** I'd like the option to generate a high-resolution model for smoother curves. This would be especially useful for visualization or 3D printing.

**Example Use Case:** I tested a prototype designed for a 1 1/2 inch fence pipe, but I also want to be able to adapt it for other sizes, like 1/2 inch PVC pipe.

**Libraries:** You are free to use any OpenSCAD libraries you deem necessary. Please specify in your response which libraries are used in the design.

Could you help me create a parametric OpenSCAD file for this design?

[Assistant]
sliderLinearBearing.scad:
```

/* Main */

// Outside bearing diameter
od=35;

// Diameter of rod
id=21.336;

// Total bearing length
length=40;

// Create higher resolution model
hires=1; // [0:No, 1:Yes]

/* Mounting grooves */

// Set to 0 for no grooves
groove_deapth=1.5;

// How far in from the ends of the bearing
groove_inset=10;

/* Spring properties */

// Probably between 1.0 and 1.3
spring_thickness=1.1;

num_springs=12;

// Add an extra twist to the spring angle
spring_twist_angle=7.5;

chamfer_size=1.5;

nub_dia=2.5; // first try was 1.5

/* [Hidden] */

// how many facets to get a smooth-ish circle at a given radius
// because the automatic internal value SUCKS!
function myFnCalc(r,hires=false)=hires?max(12,8*r):max(8,4*r);

module linear_crossection(id,od,spring_thickness,springd,num_springs,spring_od,spring_id,nub_dia,spring_twist_angle,hires){
	difference(){
		circle(r=od/2,$fn=myFnCalc(od/2,hires));
		circle(r=springd/2,$fn=myFnCalc(springd/2,hires));
	}
	intersection(){
		for(a=[0:360/num_springs:359.99]){
			rotate([0,0,a]) translate([0,-id/2,0]) rotate([0,0,-spring_twist_angle]) translate([0,-spring_od/2,0]){
				difference(){
					circle(r=spring_od/2,$fn=myFnCalc(spring_od/2,hires));
					circle(r=spring_id/2,$fn=myFnCalc(spring_id/2,hires));
					square([spring_od,spring_od]);
					translate([-spring_od/2,-spring_od]) square([spring_od,spring_od]);
				}
				translate([0,spring_od/2]) circle(r=nub_dia/2,$fn=myFnCalc(nub_dia/2,hires));
			}
		}
		circle(r=od/2,$fn=myFnCalc(od/2,hires));
	}
}

/*
if groove_inset or groove_deapth <=0 then no mounting grooves
*/
module linear(id,od,length,groove_inset=5,groove_deapth=1,spring_thickness=0.3,num_springs=5,spring_twist_angle=12.5,chamfer_size=0,nub_dia=1.5,hires=false,springd=0){
	springd=springd>id?springd:id+(od-id)*0.66;
	spring_od=id;
	spring_id=id-spring_thickness*2;
	chamfer_size=max(nub_dia/2,chamfer_size);
	// center
	translate([0,0,chamfer_size]) difference(){
		linear_extrude(length-chamfer_size*2) linear_crossection(id,od,spring_thickness,springd,num_springs,spring_od,spring_id,nub_dia,spring_twist_angle,hires);
		if(groove_inset>0&&groove_deapth>0){
			translate([0,0,groove_inset-chamfer_size]) rotate_extrude() translate([od/2,0,0]) circle(r=groove_deapth,$fn=myFnCalc(groove_deapth,hires));
			translate([0,0,length-(groove_inset+chamfer_size)]) rotate_extrude() translate([od/2,0,0]) circle(r=groove_deapth,$fn=myFnCalc(groove_deapth,hires));
		}
	}
	// top
	translate([0,0,length-chamfer_size]) {
		intersection(){
			linear_extrude(chamfer_size) linear_crossection(id,od,spring_thickness,springd,num_springs,spring_od,spring_id,0,spring_twist_angle,hires);
			cylinder(r1=od/2,r2=od/2-chamfer_size/2,h=chamfer_size,$fn=myFnCalc(od/2,hires));
		}
		for(a=[0:360/num_springs:359.99]){
			rotate([0,0,a]) {
				translate([0,-id/2,chamfer_size-nub_dia/2]) sphere(r=nub_dia/2,$fn=myFnCalc(nub_dia/2,hires));
				translate([0,-id/2,0]) cylinder(r=nub_dia/2,h=chamfer_size-nub_dia/2,$fn=myFnCalc(nub_dia/2,hires));
			}
		}
	}
	//bottom
	translate([0,0,chamfer_size]) mirror([0,0,1]) {
		intersection(){
			linear_extrude(chamfer_size) linear_crossection(id,od,spring_thickness,springd,num_springs,spring_od,spring_id,0,spring_twist_angle,hires);
			cylinder(r1=od/2,r2=od/2-chamfer_size/2,h=chamfer_size,$fn=myFnCalc(od/2,hires));
		}
		for(a=[0:360/num_springs:359.99]){
			rotate([0,0,a]) {
				translate([0,-id/2,chamfer_size-nub_dia/2]) sphere(r=nub_dia/2,$fn=myFnCalc(nub_dia/2,hires));
				translate([0,-id/2,0]) cylinder(r=nub_dia/2,h=chamfer_size-nub_dia/2,$fn=myFnCalc(nub_dia/2,hires));
			}
		}
	}
}

linear(id,od,length,groove_inset,groove_deapth,spring_thickness,num_springs,spring_twist_angle,chamfer_size,nub_dia,hires==1);
//color([0.5,0.5,0.5,0.75]) circle(r=5);
```


[User]
Hello,

I need your help designing a parametric OpenSCAD file for creating aesthetic plugs. I've got some measurements for the depth and width of the holes I need to plug, and I'm looking for a design that's both functional and visually pleasing.

Essentially, the plug should consist of two main parts: a cap and a shaft.

*   **Cap:** This is the top part of the plug that will be visible. It should be a cylinder. The diameter (`cap_diameter`) and height (`cap_height`) of the cap should be customizable.
*   **Shaft:** This is the part that goes into the hole. It should also be cylindrical. The shaft should be hollow with a customizable diameter (`shaft_diameter`), length (`shaft_length`), and wall thickness (`shaft_wall_thickness`).

The shaft should extend from the bottom of the cap. I've attached a rough OpenSCAD file as an example, but I want you to create a fully parametric one from scratch.

The final design should be adjustable using the OpenSCAD customizer. I need parameters for:

*   `shaft_diameter`: The outer diameter of the shaft.
*   `shaft_length`: The length of the shaft.
*   `shaft_wall_thickness`: The thickness of the shaft's wall.
*   `cap_diameter`: The diameter of the cap.
*   `cap_height`: The height of the cap.
*   `$fn`: The resolution of the cylinders, for smoother curves. I want to be able to choose between 100, 300, and 500.

The shaft and the cap should be rendered as a union - there should be no gap between them. The shaft should be created as the difference between two cylinders to make it hollow.

Please make use of the MCAD library.

Thank you for your assistance!

[Assistant]
plugv1.scad:
```
//shaft diameter
shaft_diameter=8;

//shaft_ length
shaft_length=7;

//shaft wall thickness
shaft_wall_thickness=1;

//cap diameter
cap_diameter=10;

//cap hight
cap_hight=3;

//resolution
$fn=300; //[100,300,500]
union(){
  cylinder ( cap_hight, d = cap_diameter );
  translate([0,0,cap_hight-.1])difference(){
   cylinder( shaft_length+.1, d=shaft_diameter);
   cylinder ( shaft_length+.2,d=(shaft_diameter-(2*shaft_wall_thickness)));
  }
}

```


[User]
I'm looking to create a ball-and-socket mount in OpenSCAD, similar to the one I found online, but I'd like it to be fully parametric so I can easily adjust it for different ball sizes and mounting requirements.

Specifically, I need:

*   **A Ball Socket:**
    *   The socket should be designed to snap onto a ball with a given diameter. I need to be able to specify this ball diameter as a parameter.
    *   There should be a clearance parameter to account for 3D printing tolerances.
    *   The opening angle of the socket should also be adjustable to control how tightly it snaps onto the ball.
    *   The wall thickness of the socket itself needs to be a parameter.
    *   I need to be able to set the vertical offset of the socket relative to the mounting surface.
    *   There should be a rounded fillet where the socket transitions to the mounting pad; the angle of this fillet should be a parameter.

*   **A Mounting Pad:**
    *   The mounting pad should be a rectangular prism.
    *   I need to control the width, length, and thickness of this pad through parameters.

*   **General Requirements:**
    *   The resolution of the part should be adjustable.
    *   The design should be adaptable so that I can easily change the dimensions via variables instead of hardcoded values, ideally with comments for each parameter to indicate what they control.

Could you generate the OpenSCAD code for this, with all the required parameters defined? The goal is a versatile ball-and-socket mount that I can customize easily. I don't need any fancy libraries, just the standard OpenSCAD functionality.

[Assistant]
BallSocketMount3.scad:
```
/* [Ball Socket] */
// Diameter of ball that socket will fit to
ballDiameter = 11.75;
// Clearance for ball socket.  This is added to the socket diameter to account for fused filament tolerances and/or part shrinking depending on plastic type
ballClearance = 0.35;
// The angle of the socket opening.  Should be less than 180 to provide a snap fit.  Too small and the ball won't be able to press into the socket.  Too large and it may fall out easily.
openingAngle = 145; // must be less than 180 for snap fit
// Thickness of the socket/cup wall
cupThickness = 1.2;
// How much space between the socket mounting surface and the edge of the ball.  If 0 then inner bottom of ball socket is on the same plane as the top of the pad.  Positive values will position the socket further away from the pad.  Negative values are not supported.
socketHeight = 0;

// Fillet angle.  To transition between the spherical socket and the flat pad, there is a rounded fillet.  This angle determines where the outside of the socket and the curved fillet meet.  Larger angles form a larger, sturdier transition.
filletAngle = 60; // [20:90]

/* [Pad] */
// Width of rectangular pad
padWidth = 15;
// Length of rectangular pad
padLength = 24;
// Thickness of rectangular pad
padThickness = 2;

// Resolution of part mesh
resolution = 0.25; // [0.2:0.1:3]

/* [Hidden] */
dBall = ballDiameter + ballClearance;

ballSocketWithPad(dBall, openingAngle, cupThickness, socketHeight, filletAngle, padWidth, padLength, padThickness, resolution);

module ballSocketWithPad(dBall, openingAngle, cupThickness, socketHeight, filletAngle, padWidth, padLength, padThickness, resolution=0.3) {
  $fs = resolution;
  $fa = 1;
  $err = 0.002;

  cupBottomOffset = cupThickness - socketHeight;
  R = dBall/2+cupThickness;
  r = (R*(1-cos(filletAngle)) - cupBottomOffset) / (1 + cos(filletAngle));

  translate([0,0,-padThickness/2]) cube([padWidth,padLength, padThickness], center=true);
  intersection() {
    ballSocket(dBall, cupThickness, openingAngle, filletAngle, socketHeight);
    // create bounds so fillet does not extend past edge of pad
    union() {
      translate([0,0,r > 0 ? r : 0]) cylinder(r=R+$err,h=R*2);
      translate([0,0,r/2]) cube([padWidth, padLength, r], center=true);
    }
  }

}

module ballSocket(dBall, cupThickness, openingAngle, filletAngle, socketHeight=0, roundedEdge = false) {
  cupBottomOffset = cupThickness - socketHeight;
  R = dBall/2+cupThickness;
  r = (R*(1-cos(filletAngle)) - cupBottomOffset) / (1 + cos(filletAngle));
  openingOffset = cos(openingAngle/2) * R;

  rotate([180,0]) translate([0,0,-R+cupBottomOffset]) rotate_extrude(convexity=3)
    union() {
      intersection() {
        difference() {
          union() {
            circle(d=dBall+2*cupThickness, center=true);
            translate([0,-cupBottomOffset]) circle_fillet(R, filletAngle, cupBottomOffset);
          }
          circle(d=dBall, center=true);
        }
        rotate([0,0,-90]) angle_cut2d(openingAngle, R+socketHeight+(r>0?r:0)+$err);
        translate([0,-openingOffset+$err]) square([R+$err+(r>0?r:0)*2, R-cupBottomOffset+openingOffset+$err]);
      }

      if (roundedEdge) {
        rotate([0,0,-90+openingAngle/2]) translate([dBall/2+cupThickness/2,0])
          circle(d=cupThickness);
      }
    }
}

module circle_fillet(R, angle, offset) {
  r = (R*(1-cos(angle)) - offset) / (1 + cos(angle));
  x = r * sin(angle);
  X = R * sin(angle);
  echo(R, r);
  R2 = X-(r-x);
  if (r > 0) {
    translate([0,R-r])
      mirror([1,0]) translate([-R2-r, 0, 0]) fil_2d_i(r,180-angle,R2,$err);
  }
}

module angle_cut(angle=90, size=1000) {
  translate([0,0,-size])
    linear_extrude(2*size)
      angle_cut2d(angle, size);
}

module angle_cut2d(angle=90,size=1000) {
  x = size*cos(angle/2);
  y = size*sin(angle/2);
  polygon([[0,0],[x,y],[x,size],[-size,size],[-size,-size],[x,-size],[x,-y]]);
}

// 2d primitive for inside fillets.
module fil_2d_i(r1, angle=90, extendX=0, extendY=0, halfAlign=false, r2=0) {
  //echo(r1, r2, angle, extendX, extendY);
  r = max(r1,r2);
  s1 = (r2 == 0) ? 1 : ((r2 > r1) ? r1/r2 : 1);
  s2 = (r2 == 0) ? 1 : ((r2 > r1) ? 1 : r2/r1);
  x1 = r + extendX;
  y1 = r + extendY;
  x2 = r * sin(angle);
  y2 = r * cos(angle);
  scale([s1,s2]) difference() {
    polygon((angle > 180) ?
      [[0,0],[0,y1],[x1,y1],[x1,-r],[x2,-r]]:
      [[0,0],[0,y1],[x1,y1],[x1,y2],[x2,y2]]
    );
    rotate(halfAlign ? 90 : 0) circle(r=max(r2,r));
  }
}

// 3d polar inside fillet.
module fil_polar_i(R, r, angle=90, extendX=0,extendY=0, halfAlign=false, r2=0, angle2=90) {

  // support for angle parameter in rotate_extrude was added after release 2015.03
  // Thingiverse customizer is still on 2015.03
  angleSupport = (version_num() > 20150399) ? true : false; // Next openscad releases after 2015.03.xx will have support angle parameter
  // Using angle parameter when possible provides huge speed boost, avoids a difference operation

  //echo(R);
  render(convexity=5)
  if (angleSupport) {
    rotate([0,0,-angle/2]) rotate_extrude(angle=angle,convexity=3) {
      difference() {
        if (R<=0) {
          mirror([1,0]) translate([R-r, 0, 0]) fil_2d_i(r,angle2,extendX,extendY, halfAlign, r2);
        } else {
          translate([R-r, 0, 0]) fil_2d_i(r,angle2,extendX,extendY, halfAlign, r2);
        }
        if (R-r < 0)
          translate([-4*(r+extendX),-r]) square([4*(r+extendX),2*r+extendY+2]);
      }
    }
  } else {
    difference() {
      rotate_extrude(convexity=7) {
        difference() {
          if (R<=0) {
            mirror([1,0]) translate([R-r, 0, 0]) fil_2d_i(r,90,extendX,extendY, halfAlign, r2);
          } else {
            translate([R-r, 0, 0]) fil_2d_i(r,90,extendX,extendY, halfAlign, r2);
          }
          if (R-r < 0)
            translate([-4*(r+extendX),-r]) square([4*(r+extendX),2*r+extendY+2]);
        }
      }
      angle_cut(angle);
    }
  }
}
```


[User]
Hi, I'm looking for a customizable design for a bike light mount that I can 3D print. I've seen a few designs online, but I need one that fits my specific bike and light.

Essentially, I need a clamp that attaches to the seat tube of my bike and holds a small, cylindrical LED bike light. The light is one of those cheap aluminum ones, typically powered by CR2032 batteries. It's important that the mount allows me to adjust the light's angle relative to the seat tube, and that it's secure. The mount also needs to have holes for screws and nuts to hold it all together. I'm hoping to use M3 hardware.

Here are the parameters I'd like to be able to adjust:

**General:**

*   `HEIGHT`: The overall height of the mount.
*   `WALL_THICKNESS`: The minimum thickness of the mount's walls.
*   `SEAT_TUBE_DIAMETER`: The diameter of the bike's seat tube.
*   `SEAT_TUBE_ANGLE`: The angle of the seat tube relative to horizontal. This is key for having the light point in the correct direction.

**Light Mount:**

*   `LIGHTSCREW_DIAMETER`: The diameter of the screw hole on the light.
*   `LIGHTSCREW_HEAD_DIAMETER`: The diameter of the screw head on the light.
*   `LIGHTSCREW_INSET`: The depth the screw head is inset into the mount.
*   `LIGHTDIAMETER`: The diameter of the main body of the light that fits into the mount.
*   `LIGHT_INSET`: The depth the main body of the light is inset into the mount.

**Mounting Hardware:**

*   `GAP`: The gap between the clamp sections for tightening with screws.
*   `GAPBOX_WIDTH`: The width of the backside of the mount.
*    `SCREW_DIST`: The distance from the edge of the mount to the screw holes.
*   `SCREW_Z_OFFSET`: The vertical offset of the screw holes from the center.
*   `SCREW_DIAMETER`: The diameter of the screws used to fix the mount to the seat tube.
*   `SCREW_HEAD_DIAMETER`: The diameter of the screw heads used to fix the mount to the seat tube.
*   `SCREW_HEAD_INSET`: The depth the screw heads are inset into the mount.
*   `NUT_DIAMETER`: The diameter of the nuts used to fix the mount to the seat tube.
*   `NUT_INSET`: The depth the nuts are inset into the mount.

I'd like the mount to be designed using OpenSCAD. I am not using any specific libraries, so please don't include any library calls.

Could you generate the necessary OpenSCAD code? Thanks!

[Assistant]
bikelightmount.scad:
```
/* Bike light mount
 *
 * https://github.com/lumbric/bikelightmount
 * http://www.thingiverse.com/thing:1566371
 *
 * This is a costumizeable bike light holder inspired by the
 * [31.6mm bike light holder](http://www.thingiverse.com/thing:1487051). My
 * seat tube is too thin, so I redesigned it in OpenScad and made it
 * costumizeable.
 *
 * You need:
 *   - 2 M3 nuts
 *   - 2 screws, ~16-20mm lenght
 *   - aluminum LED bike light
 *
 * These aluminum LED bike lights are very wide spread and very cheap. Just
 * search on ebay or aliexpress. They are powered by 2x CR2032 batteries
 * lasting for quite a while if you use them in flashing mode. They are also
 * bright enough for the rear light, but I would not recommend them for your
 * front light. Note that sizes very a bit, you might need to adapt the
 * parameters LIGHTDIAMETER and LIGHT_INSET. There are also USB chargeable
 * ones out there, but I don't have one to try if the model fits.
 *
 *
 * This work is licensed under the Creative Commons Attribution-ShareAlike 4.0
 * International License. To view a copy of this license, visit
 * http://creativecommons.org/licenses/by-sa/4.0/.
 *
 */

/* [General] */

// height in mm
HEIGHT = 16.;               // [5:40]

// thickness of thinest part of the wall in mm
WALL_THICKNESS = 1.;        // [0.2:10]

// diameter of the seat tube in mm
SEAT_TUBE_DIAMETER = 26.5;   // [20:40]

// angle of your seat tube to mount the light horizontal (in degrees)
SEAT_TUBE_ANGLE = 10.;      // [0:45]

/* [Front - light] */

// diameter of screw, which is screwed to light (in mm)
LIGHTSCREW_DIAMETER = 5.2;   // [1:18]

// diameter of head of screw, which is screwed to light (in mm)
LIGHTSCREW_HEAD_DIAMETER = 9.5;   // [1:18]

// height of head of screw for light (in mm)
LIGHTSCREW_INSET = 2.3;   // [0:12]

// diameter of bottom of light (in mm), other version with 8.8mm
LIGHTDIAMETER = 10.75;    // [1:25]

// height of bottom of light (in mm)
LIGHT_INSET = 2.7;        // [0:12]

/* [Back - screws and nuts] */

// gap, used for tightening with screws (in mm)
GAP = 7.;                 // [2:15]

// with of backside of bike light mount (in mm)
GAPBOX_WIDTH = HEIGHT;

// distance from edge to seat tube + WALL_THICKNESS on backside (in mm)
SCREW_DIST = 4.9;          // [1:15]

// how much screw holes are moved up and down from center (in mm)
SCREW_Z_OFFSET = 0.25 * HEIGHT;   // [0:15]

// diameter of screws used to fix bikelightmount (in mm)
SCREW_DIAMETER = 3.2;       // [1:8]

// diameter of head of both screws used to fix bikelightmount (in mm)
SCREW_HEAD_DIAMETER = 6.4;   // [1:12]

// height of screw head (in mm), use less than SCREW_HEAD_INSET <= (GAPBOX_WIDTH - GAP)/2. - WALL_THICKNESS
SCREW_HEAD_INSET = 2.;      // [1:12]

// diameter of nut in mm (about 6mm for M3)
NUT_DIAMETER = 6.4;          // [1:12]

// height of nut in mm (usually about 2mm for M3), use less then NUT_INSET <= (GAPBOX_WIDTH - GAP)/2. - WALL_THICKNESS
NUT_INSET = 2.;             // [1:12]

/* [Hidden] */

// thickness of wall separating light and screw head
wall_thickness_lightscrew = WALL_THICKNESS;

// distance of
light_dist = LIGHTSCREW_INSET + LIGHT_INSET + wall_thickness_lightscrew - WALL_THICKNESS;

$fn=200;

bikelight_mount();
/*%seattube();  // will not be printed*/

/**
 * Bike light mount. This is what you want to print.
 */
module bikelight_mount() {
    difference() {
        base();
        seattube();
        gap();

        screws();
        lightscrew();
    }
}

/**
 * Base object. Need to cut out holes for screws and seat tube and gap.
 */
module base() {
    hull() {
        intersection() {
            outer_diameter = 3*SEAT_TUBE_DIAMETER;
            cube([outer_diameter, outer_diameter, HEIGHT], center=true);

            rotate([SEAT_TUBE_ANGLE, 0., 0.])
                cylinder(h=10*HEIGHT,
                        d=SEAT_TUBE_DIAMETER + 2*WALL_THICKNESS,
                        center=true);
        }
        translate([0., WALL_THICKNESS + SEAT_TUBE_DIAMETER/2., 0.])
            cube([HEIGHT, 2*SCREW_DIST, HEIGHT], center=true);

        translate([0., -WALL_THICKNESS -SEAT_TUBE_DIAMETER/2., 0.])
            cube([GAPBOX_WIDTH, 2*light_dist, HEIGHT], center=true);
    }
}

/**
 * Screw for mounting the light (screwed in light) and light bottom. Object
 * used subtracting, i.e. making the hole for the screw.
 */
module lightscrew() {
    translate([0., -WALL_THICKNESS-light_dist-SEAT_TUBE_DIAMETER/2., 0.])
        rotate([90., 0., 0.])
            cylinder(d=LIGHTDIAMETER, h=2*LIGHT_INSET, center=true);
    translate([0., -SEAT_TUBE_DIAMETER/2., 0.])
        rotate([90., 0., 0.])
            cylinder(d=LIGHTSCREW_HEAD_DIAMETER, h=2*LIGHTSCREW_INSET, center=true);
    translate([0., -SEAT_TUBE_DIAMETER/2., 0.])
        rotate([90., 0., 0.])
            cylinder(d=LIGHTSCREW_DIAMETER, h=SEAT_TUBE_DIAMETER, center=true);
}

module gap() {
    translate([0., SEAT_TUBE_DIAMETER/2., 0.])
        cube([GAP, SEAT_TUBE_DIAMETER, 3*HEIGHT], center=true);
}

module seattube() {
    rotate([SEAT_TUBE_ANGLE, 0., 0.])
        translate([0., 0., -HEIGHT])
            cylinder(h=10*HEIGHT, d=SEAT_TUBE_DIAMETER, center=true);
}

/**
 * Screws and nuts.
 */
module screws() {
    screw();
    mirror([0., 0., 1.])
        screw();
}

module screw() {
    translate([0.,
            SCREW_DIST/2. + SEAT_TUBE_DIAMETER/2.,
            SCREW_Z_OFFSET]) {
        rotate([0., 90., 0.])
            cylinder(d=SCREW_DIAMETER, h=SEAT_TUBE_DIAMETER, center=true);

        translate([GAPBOX_WIDTH - SCREW_HEAD_INSET, 0., 0.])
            rotate([0., 90., 0.])
                cylinder(d=SCREW_HEAD_DIAMETER, h=GAPBOX_WIDTH, center=true);

        translate([-GAPBOX_WIDTH + NUT_INSET, 0., 0.])
            rotate([0., 90., 0.])
                cylinder(d=NUT_DIAMETER, h=GAPBOX_WIDTH, center=true, $fn=6);
    }
}

```


[User]
Hey, I'm looking to design some custom motor protectors for my quadcopter, and I'd like to use OpenSCAD to make them fully parametric. I've got the design I'm aiming for roughly in mind, and I have an example SCAD file, but it's a bit messy, and I'd like a cleaner, more modular approach.

Essentially, I need to create a cylindrical protector that fits around the motor mount. This protector needs to have cutouts for the motor shaft, the mounting screws, and the arm of the quadcopter frame. I'd like to be able to adjust the following parameters:

*   **Screw Dimensions:**
    *   Diameter of the mounting screws.
    *   Distance between screw centers.
    *   The length of the "slide" for the screw cutouts - that is, how much the cut extends along a line.
    *   The rotational angle of the screw fixing points.
*   **Motor Dimensions:**
    *   Diameter of the motor shaft (with some tolerance).
*   **Arm Dimensions:**
    *   Diameter of the arm where it meets the motor mount.
    *   Width of the arm.
*   **Protector Dimensions:**
    *   Overall diameter of the protector.
    *   Height of the protector.
    *   Thickness of the bottom part of the protector.
*   **General Settings:**
    *   General resolution/smoothness for curves
    *   Resolution for the protector's outer shape.

The design should be built using a subtractive method - that is, I'd like a solid cylinder and then to subtract the cutouts from it. I'd also like to be able to rotate the whole design to view it from different angles while editing.

Could you create an OpenSCAD file (or files) for me that handles all this?  It would be great if it was well-organized and easy to modify. I'd like for all the code to be in a single `.scad` file if possible.

[Assistant]
Emax_Motor_Protector_V2.scad:
```
/*
Customisable Motor Protection for Quadcopter

    - by Harlo
    - 16/05/2016

    **Standard variables are based on an Emax Nighthawk 250**
*/

//Fixing Screws Diameter
screw_dia = 3.5; //[0:0.25:8]
//Distance Between Screw Centers
screw_seperation = 17; //[0:0.25:50]
//Screw Slide Distance
screw_slide = 3; //[0:0.25:10]
//Rotate the fixings (degrees)
screw_rotation = 0; //[0:1:90]
//Motor Shaft Diameter (add tolerance)
shaft_dia = 9; //[0:0.25:15]
//Arm Diameter (of mount)
arm_dia = 30; //[5:0.25:80]
//Arm Width
arm_width = 25.25; //[3:0.25:80]
//General Smoothness
resolution = 80; //[20:1:180]
//Outside Diameter
protector_dia = 35; //[20:0.25:120]
//Outer Shape/Smoothness
protector_res = 8; //[8:1:180]
//Protector Height (Total Z)
protector_height = 10; //[1:0.1:60]
//Protector Lower Thickness
protector_bottom_thickness = 2; //[0.5:0.1:10]
//Rotate (for viewing while editing)
turn = -90; //[0:15:360]

//Internal Variables
arm_length = arm_dia*3;
screw_height = 20 * 1;
arm_thickness = 20 * 1;
shaft_height = 20 * 1;

//Render
rotate([0,0,turn]){
    protector_with_cuts();
}

//Modules

module protector_with_cuts(){
    difference(){
        protector();
        cut_arm();
        cut_base();
        cut_screws();
        cut_shaft();
    }
}

module protector(){
    translate([0,0,protector_height/2 - protector_bottom_thickness]){
        cylinder(h = protector_height, d = protector_dia, center = true, $fn = protector_res);
    }
}

//CUTTING Modules
module cut_shaft(){
    cylinder(h = shaft_height, d = shaft_dia, center = true, $fn = resolution);
}

module cut_screws(){
    rotate([0,0,screw_rotation]){
        screw_placed();
        rotate([0,0,90]){
            screw_placed();
        }
    }
}

module screw_placed(){
    translate([screw_seperation/2,0,0]){
        screw_slide();
    }

    translate([-screw_seperation/2,0,0]){
        screw_slide();
    }
}

module screw_slide(){
    hull(){
        translate([screw_slide/2,0,0]){
            screw(screw_height, screw_dia);
        }
        translate([-screw_slide/2,0,0]){
            screw(screw_height, screw_dia);
        }
    }
}

module screw(height, diameter){
    cylinder(h = height, d = diameter, $fn = resolution, center = true);
}

module cut_base(){
    translate([0,0,arm_thickness/2]){
        cylinder(h = arm_thickness, d = arm_dia, $fn = resolution, center = true);
    }
}

module cut_arm(){
    translate([arm_length/2,0,arm_thickness/2]){
        cube([arm_length, arm_width, arm_thickness], center = true);
    }
}
```


[User]
I'd like to create a parametric design for a lightweight, tension-fit shelf that can be installed inside a window frame using dowel rods. The design should be based around these elements:

*   **Dowel Rods:** The primary structural component, with a specified diameter. I'm using 3/8 inch rods, which is about 9.53mm. The design needs to accommodate a specific number of these rods running parallel to each other, which will define the shelf's depth.
*   **End Caps:** These will hold the dowel rods in place and provide a surface for the tensioning mechanism, and need to have both a static and dynamic side. The static end should create a pocket to hold the rod end. The dynamic end needs to both hold the dowel rod and also have a threaded section that allows for adjustable tension against a static end.  I want to be able to set the depth of the rod pocket and the wall thickness of the end cap independently. The threaded section should be a trapezoidal thread, and the length of the threaded section should be adjustable too.
*   **Spacers:** These will maintain the dowel rods' parallel alignment and define the shelf's width. The spacers should have cutouts that accommodate the dowel rods, and the top of the spacer should be a different thickness than the body where the dowel rod goes through it. The spacers also need to be adjustable in terms of the total length/depth of the shelf.

Specifically, I'm looking for an OpenSCAD design that lets me customize the following parameters:

*   `rod_diam`: Diameter of the dowel rod (e.g., 9.53mm).
*   `cap_depth`: How deep the pocket is in the end cap to hold the rod.
*   `cap_thickness`: The wall thickness of the end cap (must be less than half of rod_diameter).
*    `extend_distance`: How far out the threaded rod extends from the end cap.
*   `depth`: The depth of the shelf.
*   `width`: The width of the top piece of the spacer.
*   `top_thickness`: The thickness of the top piece of the spacer.
*  `spacer_thickness`: The thickness of the portion of the spacer where the dowel rod goes through.
*   `num_rods`: The number of dowel rods.
*   `num_spacers`: The number of spacers.
*  `resolution`: How many segments to break circular paths into.
*   `extra_space`: Extra space for the threaded rod.

The design should include the following modules:

*   `static_end()`: Creates the static end cap piece with the rod pocket.
*   `dynamic_end_cap()`: Creates the dynamic end cap piece with the threaded section, should call the `static_end()` module for the end cap shape.
*  `dynamic_end_rod()`: Creates the threaded rod, the piece that would screw into the `dynamic_end_cap()`.
*   `rodHull()`: A small module to generate the cutouts in the spacers.
*   `spacer()`: Creates a spacer piece with holes for dowel rods
*   `all_parts()`: Creates an instance of all the parts of the shelf.
*   `trapezoidThread()` and `trapezoidThreadNegativeSpace()` from the supplied file.

I'd also like it if you could make use of the `trapezoidThread()` module as defined in the attached code.

Essentially, the output should be a set of parametric parts that I can use to construct the shelf with different dimensions.

[Assistant]
dowelrodshelfComplete.scad:
```
// diameter of the doll rod
rod_diam = 9.53;

//how deep of a pocket to make for the doll rod
cap_depth = 10;

// how thick of a cap wall to have, must be less that 1/2 of rod_diameter
cap_thickness = 3;

// how much distance the screw end should extend
extend_distance = 20;

// Depth of the shelf you want to make
depth = 100;

// width of the spacer top piece
width = 20;

// thickness of the top piece of the spacer
top_thickness = 2;

// thickness of portion of the spacer where the rod goes through
spacer_thickness = 2;

// number or rods in the shelf
num_rods = 4;

// number of spacers you want to add
num_spacers = 4;

// how many segments to break circular paths into
resolution=24;

//Extra space to leave for the threaded rod
extra_space=0.175;
/// THANKS FOR THE THREAD LIBRARY FROM SYVWLCH available at http://www.thingiverse.com/thing:8793
module threadPiece(Xa, Ya, Za, Xb, Yb, Zb, radiusa, radiusb, tipRatioa, tipRatiob, threadAngleTop, threadAngleBottom)
{
	angleZ=atan2(Ya, Xa);
	twistZ=atan2(Yb, Xb)-atan2(Ya, Xa);

	polyPoints=[
		[Xa+ radiusa*cos(+angleZ),		Ya+ radiusa*sin(+angleZ),		Za ],
		[Xa+ radiusa*cos(+angleZ),		Ya+ radiusa*sin(+angleZ),		Za + radiusa*tipRatioa ],
		[Xa ,						Ya ,						Za+ radiusa*(tipRatioa+sin(threadAngleTop)) ],
		[Xa ,						Ya ,						Za ],
		[Xa ,						Ya ,						Za+ radiusa*sin(threadAngleBottom) ],

		[Xb+ radiusb*cos(angleZ+twistZ),	Yb+ radiusb*sin(angleZ+twistZ),	Zb ],
		[Xb+ radiusb*cos(angleZ+twistZ),	Yb+ radiusb*sin(angleZ+twistZ),	Zb+ radiusb*tipRatiob ],
		[Xb ,						Yb ,						Zb+ radiusb*(tipRatiob+sin(threadAngleTop)) ],
		[Xb ,						Yb ,						Zb ],
		[Xb ,						Yb ,						Zb+ radiusb*sin(threadAngleBottom)] ];

	polyTriangles=[
		[ 0, 1, 6 ], [ 0, 6, 5 ], 					// tip of profile
		[ 1, 7, 6 ], [ 1, 2, 7 ], 					// upper side of profile
		[ 0, 5, 4 ], [ 4, 5, 9 ], 					// lower side of profile
		[ 4, 9, 3 ], [ 9, 8, 3 ], [ 3, 8, 2 ], [ 8, 7, 2 ], 	// back of profile
		[ 0, 4, 3 ], [ 0, 3, 2 ], [ 0, 2, 1 ], 			// a side of profile
		[ 5, 8, 9 ], [ 5, 7, 8 ], [ 5, 6, 7 ]  			// b side of profile
		 ];

	polyhedron( polyPoints, polyTriangles );
}

module shaftPiece(Xa, Ya, Za, Xb, Yb, Zb, radiusa, radiusb, tipRatioa, tipRatiob, threadAngleTop, threadAngleBottom)
{
	angleZ=atan2(Ya, Xa);
	twistZ=atan2(Yb, Xb)-atan2(Ya, Xa);

	threadAngleTop=15;
	threadAngleBottom=-15;

	shaftRatio=0.5;

	polyPoints1=[
		[Xa,						Ya,						Za + radiusa*sin(threadAngleBottom) ],
		[Xa,						Ya,						Za + radiusa*(tipRatioa+sin(threadAngleTop)) ],
		[Xa*shaftRatio,				Ya*shaftRatio ,				Za + radiusa*(tipRatioa+sin(threadAngleTop)) ],
		[Xa*shaftRatio ,				Ya*shaftRatio ,				Za ],
		[Xa*shaftRatio ,				Ya*shaftRatio ,				Za + radiusa*sin(threadAngleBottom) ],

		[Xb,						Yb,						Zb + radiusb*sin(threadAngleBottom) ],
		[Xb,						Yb,						Zb + radiusb*(tipRatiob+sin(threadAngleTop)) ],
		[Xb*shaftRatio ,				Yb*shaftRatio ,				Zb + radiusb*(tipRatiob+sin(threadAngleTop)) ],
		[Xb*shaftRatio ,				Yb*shaftRatio ,				Zb ],
		[Xb*shaftRatio ,				Yb*shaftRatio ,				Zb + radiusb*sin(threadAngleBottom) ] ];

	polyTriangles1=[
		[ 0, 1, 6 ], [ 0, 6, 5 ], 					// tip of profile
		[ 1, 7, 6 ], [ 1, 2, 7 ], 					// upper side of profile
		[ 0, 5, 4 ], [ 4, 5, 9 ], 					// lower side of profile
		[ 3, 4, 9 ], [ 9, 8, 3 ], [ 2, 3, 8 ], [ 8, 7, 2 ], 	// back of profile
		[ 0, 4, 3 ], [ 0, 3, 2 ], [ 0, 2, 1 ], 			// a side of profile
		[ 5, 8, 9 ], [ 5, 7, 8 ], [ 5, 6, 7 ]  			// b side of profile
		 ];

	// this is the back of the raised part of the profile
	polyhedron( polyPoints1, polyTriangles1 );
}

module trapezoidThread(
	length=45,				// axial length of the threaded rod
	pitch=10,				// axial distance from crest to crest
	pitchRadius=10,			// radial distance from center to mid-profile
	threadHeightToPitch=0.5,	// ratio between the height of the profile and the pitch
						// std value for Acme or metric lead screw is 0.5
	profileRatio=0.5,			// ratio between the lengths of the raised part of the profile and the pitch
						// std value for Acme or metric lead screw is 0.5
	threadAngle=30,			// angle between the two faces of the thread
						// std value for Acme is 29 or for metric lead screw is 30
	RH=true,				// true/false the thread winds clockwise looking along shaft, i.e.follows the Right Hand Rule
	clearance=0.1,			// radial clearance, normalized to thread height
	backlash=0.1,			// axial clearance, normalized to pitch
	stepsPerTurn=24			// number of slices to create per turn
		)
{

	numberTurns=length/pitch;

	steps=stepsPerTurn*numberTurns;

	trapezoidRatio=				2*profileRatio*(1-backlash);

	function	threadAngleTop(i)=	threadAngle/2;
	function	threadAngleBottom(i)=	-threadAngle/2;

	function 	threadHeight(i)=		pitch*threadHeightToPitch;

	function	pitchRadius(i)=		pitchRadius;
	function	minorRadius(i)=		pitchRadius(i)-0.5*threadHeight(i);

	function 	X(i)=				minorRadius(i)*cos(i*360*numberTurns);
	function 	Y(i)=				minorRadius(i)*sin(i*360*numberTurns);
	function 	Z(i)=				pitch*numberTurns*i;

	function	tip(i)=			trapezoidRatio*(1-0.5*sin(threadAngleTop(i))+0.5*sin(threadAngleBottom(i)));

	// this is the threaded rod

	if (RH==true)
	translate([0,0,-threadHeight(0)*sin(threadAngleBottom(0))])
	for (i=[0:steps-1])
	{
		threadPiece(
			Xa=				X(i/steps),
			Ya=				Y(i/steps),
			Za=				Z(i/steps),
			Xb=				X((i+1)/steps),
			Yb=				Y((i+1)/steps),
			Zb=				Z((i+1)/steps),
			radiusa=			threadHeight(i/steps),
			radiusb=			threadHeight((i+1)/steps),
			tipRatioa=			tip(i/steps),
			tipRatiob=			tip((i+1)/steps),
			threadAngleTop=		threadAngleTop(i),
			threadAngleBottom=	threadAngleBottom(i)
			);

		shaftPiece(
			Xa=				X(i/steps),
			Ya=				Y(i/steps),
			Za=				Z(i/steps),
			Xb=				X((i+1)/steps),
			Yb=				Y((i+1)/steps),
			Zb=				Z((i+1)/steps),
			radiusa=			threadHeight(i/steps),
			radiusb=			threadHeight((i+1)/steps),
			tipRatioa=			tip(i/steps),
			tipRatiob=			tip((i+1)/steps),
			threadAngleTop=		threadAngleTop(i),
			threadAngleBottom=	threadAngleBottom(i)
			);
	}

	if (RH==false)
	translate([0,0,-threadHeight(0)*sin(threadAngleBottom(0))])
	mirror([0,1,0])
	for (i=[0:steps-1])
	{
		threadPiece(
			Xa=				X(i/steps),
			Ya=				Y(i/steps),
			Za=				Z(i/steps),
			Xb=				X((i+1)/steps),
			Yb=				Y((i+1)/steps),
			Zb=				Z((i+1)/steps),
			radiusa=			threadHeight(i/steps),
			radiusb=			threadHeight((i+1)/steps),
			tipRatioa=			tip(i/steps),
			tipRatiob=			tip((i+1)/steps),
			threadAngleTop=		threadAngleTop(i),
			threadAngleBottom=	threadAngleBottom(i)
			);

		shaftPiece(
			Xa=				X(i/steps),
			Ya=				Y(i/steps),
			Za=				Z(i/steps),
			Xb=				X((i+1)/steps),
			Yb=				Y((i+1)/steps),
			Zb=				Z((i+1)/steps),
			radiusa=			threadHeight(i/steps),
			radiusb=			threadHeight((i+1)/steps),
			tipRatioa=			tip(i/steps),
			tipRatiob=			tip((i+1)/steps),
			threadAngleTop=		threadAngleTop(i),
			threadAngleBottom=	threadAngleBottom(i)
			);
	}

	rotate([0,0,180/stepsPerTurn])
	cylinder(
		h=length+threadHeight(1)*(tip(1)+sin( threadAngleTop(1) )-1*sin( threadAngleBottom(1) ) ),
		r1=minorRadius(0)-clearance*threadHeight(0),
		r2=minorRadius(0)-clearance*threadHeight(0),
		$fn=stepsPerTurn
			);
}

module trapezoidThreadNegativeSpace(
	length=45,				// axial length of the threaded rod
	pitch=10,				// axial distance from crest to crest
	pitchRadius=10,			// radial distance from center to mid-profile
	threadHeightToPitch=0.5,	// ratio between the height of the profile and the pitch
						// std value for Acme or metric lead screw is 0.5
	profileRatio=0.5,			// ratio between the lengths of the raised part of the profile and the pitch
						// std value for Acme or metric lead screw is 0.5
	threadAngle=30,			// angle between the two faces of the thread
						// std value for Acme is 29 or for metric lead screw is 30
	RH=true,				// true/false the thread winds clockwise looking along shaft, i.e.follows the Right Hand Rule
	countersunk=0,			// depth of 45 degree chamfered entries, normalized to pitch
	clearance=0.1,			// radial clearance, normalized to thread height
	backlash=0.1,			// axial clearance, normalized to pitch
	stepsPerTurn=24			// number of slices to create per turn
		)
{

	translate([0,0,-countersunk*pitch])
	cylinder(
		h=2*countersunk*pitch,
		r2=pitchRadius+clearance*pitch+0.25*pitch,
		r1=pitchRadius+clearance*pitch+0.25*pitch+2*countersunk*pitch,
		$fn=24
			);

	translate([0,0,countersunk*pitch])
	translate([0,0,-pitch])
	trapezoidThread(
		length=length+0.5*pitch, 				// axial length of the threaded rod
		pitch=pitch, 					// axial distance from crest to crest
		pitchRadius=pitchRadius+clearance*pitch, 	// radial distance from center to mid-profile
		threadHeightToPitch=threadHeightToPitch, 	// ratio between the height of the profile and the pitch
									// std value for Acme or metric lead screw is 0.5
		profileRatio=profileRatio, 			// ratio between the lengths of the raised part of the profile and the pitch
									// std value for Acme or metric lead screw is 0.5
		threadAngle=threadAngle,			// angle between the two faces of the thread
									// std value for Acme is 29 or for metric lead screw is 30
		RH=true, 						// true/false the thread winds clockwise looking along shaft
									// i.e.follows  Right Hand Rule
		clearance=0, 					// radial clearance, normalized to thread height
		backlash=-backlash, 				// axial clearance, normalized to pitch
		stepsPerTurn=stepsPerTurn 			// number of slices to create per turn
			);

	translate([0,0,length-countersunk*pitch])
	cylinder(
		h=2*countersunk*pitch,
		r1=pitchRadius+clearance*pitch+0.25*pitch,
		r2=pitchRadius+clearance*pitch+0.25*pitch+2*countersunk*pitch,$fn=24,
		$fn=24
			);
}
// END OF library

module static_end() {
    union() {
        cylinder(r=rod_diam, h=2, $fn=resolution);
        difference() {
            cylinder(r=rod_diam/2+cap_thickness, h=2+cap_depth, $fn=resolution);
            translate([0,0,2]) cylinder(r=rod_diam/2, h=cap_depth+0.001, $fn=resolution);
        }
    }
}

module dynamic_end_cap() {
    union() {
       translate([0,0,extend_distance]) static_end();
       difference() {
           cylinder(r=rod_diam, h=extend_distance, $fn=resolution);
           trapezoidThreadNegativeSpace(
                    length=extend_distance,
                    pitch = 2.5,
                    pitchRadius=(rod_diam-cap_thickness)/2,
                    clearance=extra_space,
                    stepsPerTurn=resolution);
       }
   }
}

module dynamic_end_rod() {
    union() {
        cylinder(r=rod_diam, h=2, $fn=50);
        cylinder(r=rod_diam/2+cap_thickness, h=2+cap_depth, $fn=resolution);
        translate([0,0,cap_depth])
            trapezoidThread(
                length=extend_distance,
                radius=rod_diam,
                pitch = 2.5,
                pitchRadius=(rod_diam-cap_thickness)/2,
                stepsPerTurn=resolution);
    }
}

module rodHull(){
    translate([-0.1,0,top_thickness+rod_diam/2])
        rotate([0,90,0])
            cylinder(r=rod_diam*1.025/2, h=width+0.2, $fn=50);
}

module spacer() {
    difference() {
        union() {
            cube([width, depth, top_thickness]);
            translate([(width-spacer_thickness)/2, 0, top_thickness])
                cube([spacer_thickness, depth, rod_diam*1.1]);
        }
        for (a = [1:num_rods]) {
            translate([0,(depth/(num_rods+1))*a, 0]) rodHull();
        }
    }
}

module all_parts() {
    for (a = [0:num_rods-1]) {
        translate([0,a*2*(rod_diam*1.1)+rod_diam,0])
            static_end();
        translate([2*(rod_diam+2), a*2*(rod_diam*1.1)+rod_diam, 0])
            dynamic_end_cap();
        translate([-2*(rod_diam+2), a*2*(rod_diam*1.1)+rod_diam, 0])
            dynamic_end_rod();
    }
    for (b = [1:num_rods]) {
        translate([depth/2,(-1*b*width*1.1),0])
            rotate([0,0,90])
                spacer();
    }
}
all_parts();
```