module Tetrahedron(L) {
  cylinder(r1=L/sqrt(3), r2=0, h=L*sqrt(6)/3, $fn=3);
}

module Octahedron(L) {
  render() {
    cylinder(r1=L/sqrt(2), r2=0, h=L/sqrt(2), $fn=4);
    mirror([0,0,1]) cylinder(r1=L/sqrt(2), r2=0, h=L/sqrt(2), $fn=4);
  }
}

module PentagonalTrapezohedron(L) {
  rw = (10/9)*(2*L+L/sqrt(2));
  h = 2*L+L/sqrt(2);
  render() intersection() {
    translate([0,0,-2*L])
      cylinder(r1=rw, r2=0, h=h, $fn=5);
    mirror([0,0,1]) rotate([0,0,36]) translate([0,0,-2*L])
      cylinder(r1=rw, r2=0, h=h, $fn=5);
  }
}
module Decahedron(L) {
  PentagonalTrapezohedron(L);
}
module Rounded10d(L, roundby) {
  minkowski() {
    sphere(r=roundby, $fs=0.2);
    PentagonalTrapezohedron(L-roundby);
  }
}


Tetrahedron(10);
translate([15,0,0]) Octahedron(10);
translate([32,0,0]) Rounded10d(10, 1);