// Rubber attachment for track element, something like lego 14149
// (c) Vitaliy Filippov, 2014, license: GPL 3.0+

$fn=20;
difference() {
  union() {
    hull() {
      cylinder(r=2.4, h=4);
      translate([0, 16, 0]) cylinder(r=2.4, h=4);
      translate([0, 0, 3]) cylinder(r=4, h=1);
      translate([0, 16, 3]) cylinder(r=4, h=1);
    }
    cylinder(r=2.4, h=9);
    translate([0, 16, 0]) cylinder(r=2.4, h=9);
    translate([0, 0, 8.3]) hull() {
      cylinder(r=2.8, h=1);
      translate([0, 0, -0.6]) cylinder(r=2.4, h=1+0.6*2);
    }
    translate([0, 16, 8.3]) hull() {
      cylinder(r=2.8, h=1);
      translate([0, 0, -0.6]) cylinder(r=2.4, h=1+0.6*2);
    }
  }
  hull() {
    translate([4, 0, 8.5]) scale([8, 1, 1]) rotate([-90, 0, 90]) wedge();
    translate([-4, -0.5, 8.5]) cube(size=[8, 1, 4]);
  }
  hull() {
    translate([4, 16, 8.5]) scale([8, 1, 1]) rotate([-90, 0, 90]) wedge();
    translate([-4, 16-0.5, 8.5]) cube(size=[8, 1, 4]);
  }
  translate([2.4, -4, 7]) cube(size=[2, 8, 4]);
  translate([-2.4-2, -4, 7]) cube(size=[2, 8, 4]);
  translate([2.4, 16-4, 7]) cube(size=[2, 8, 4]);
  translate([-2.4-2, 16-4, 7]) cube(size=[2, 8, 4]);
}

module wedge() {
  linear_extrude(height=1) polygon(points=[[-0.5, 0], [0.5, 0], [0, 1]]);
}