mm_per_inch = 25.4;

material_width = (1/8) * mm_per_inch;

board_length = 1.75 * mm_per_inch;
board_width = 1.5 * mm_per_inch;
board_depth = (3/16) * mm_per_inch;
tab_length = 3 * mm_per_inch;
tab_width = (1/4) * mm_per_inch;

union(){
  rotate(a = 90, v = [1, 0, 0]) {
    cube([board_length + material_width,
          1.75 * mm_per_inch + material_width,
          material_width ]);}

  translate(v = [0, -material_width, 0]){
    rotate(a = -90, v = [0, 1, 0]) {
      cube( [1.75 * mm_per_inch + material_width,
             1.5 * mm_per_inch + 2 * material_width,
             material_width ]);}}

  translate(v = [(1.75*mm_per_inch + material_width)/2 + tab_width,
                 -tab_length, 0]){
    rotate(a = 90, v = [0 ,0 ,1 ]){
      cube([3*mm_per_inch, 0.5*mm_per_inch , material_width]);}}

  translate(v = [-tab_length,
                 (1.5*mm_per_inch + material_width)/2 - tab_width,
                 0]){
    cube([3*mm_per_inch, 0.5*mm_per_inch , material_width]);}

  translate(v = [(1.75*mm_per_inch + material_width)/2 + tab_width,
                 (1.5*mm_per_inch),
                 0]){
    rotate(a = 90, v = [0, 0, 1]){
      cube([3*mm_per_inch, 0.5*mm_per_inch , material_width]);}}

  translate(v = [(1.75*mm_per_inch),
                 (1.5*mm_per_inch+material_width)/2 - tab_width,
                 0]){
    cube([3*mm_per_inch, 0.5*mm_per_inch , material_width]);}}

_4_40 = 0.1285*mm_per_inch/2; // size of hole for 4x40
_6_32 = 0.1495*mm_per_inch/2; // size of hole for 6x32

module collar_hole(){
  cylinder(h = board_depth, r = 2*_6_32, $fn=20);}

module nubbin_hole(){
  cylinder(h = board_depth, r = _6_32, $fn=20);}

module mounting_screw_hole(){
  cylinder(h = board_depth, r = _6_32, $fn=20);}

module bracket_screw_hole(){
  cylinder(h = board_depth, r = _6_32, $fn=20);}

module wheel_motor_holes(scale){
  translate([ 51-26.78,38-10.8, 0] * scale) {
    collar_hole();}
  translate([ 51-26.78,38-22.23, 0] * scale){
    nubbin_hole();}
  translate([51-18.05-17.45,38-30.81,  0] * scale){
    mounting_screw_hole();}
  translate([51-18.05,38-30.81, 0] * scale){
    mounting_screw_hole();}
  translate([7.5,8.5, 0] * scale){
    bracket_screw_hole();}
  translate([7.5,21+8.5,   0] * scale){
    bracket_screw_hole();}}

module wheel_mount(scale){
  difference(){
    cube(scale * [board_length + material_width,
                  board_width + material_width,
                  material_width]);
    wheel_motor_holes(scale);}}

wheel_mount(1);

translate(v = [0, 0, board_length]) jig_lid();

module jig_lid() {
  union() {
    wheel_mount(1);
    translate(v = [0, -2.1 * material_width, material_width]){
      cube([board_length + material_width,
            3.1 * material_width,
            material_width]);}
    translate(v = [0, -2.1 * material_width, 0]){
      cube([board_length + material_width, material_width, material_width]);}
    translate(v = [-2.1 * material_width, 0, material_width]){
      cube([3.1 * material_width,
            board_width + material_width,
            material_width]);}
    translate(v = [-2.1 * material_width, 0, 0]){
      cube([material_width, board_width+material_width, material_width]);}}}