$fn=4;

ofaces = [
  [0, 1, 2], [0, 2, 4], [0, 4, 5], [0, 5, 1], 
  [3, 5, 4], [3, 1, 5], [3, 2, 1], [3, 4, 2],
];	

edges = [[0, 1], [0, 2], [0, 4], [0, 5], [3, 1], [3, 2], [3, 4], [3, 5], [1, 2], [2, 4], [4, 5], [5, 1]];


module octahedron(center, size) {
  points = [
    center + [l / 2, 0, 0], center + [0, l / 2, 0], center + [0, 0, l / 2],
    center - [l / 2, 0, 0], center - [0, l / 2, 0], center - [0, 0, l / 2],
  ];
  polyhedron(points=points, faces=ofaces, convexity=1);
}

module tetrahedron(points) {
  polyhedron(points=points, faces=[[1, 2, 3],[0, 1, 3],[0, 2, 1],[0, 3, 2]], convexity=1);
}

function sumv(v, i=0) = (i + 1 == len(v)? v[i]: v[i] + sumv(v, i + 1));
//function sumsqv(v, i=0) = (i + 1 == len(v)? v[i] * v[i]: v[i] * v[i] + sumsqv(v, i + 1));
function length(v) = sqrt( pow(v[0], 2) + pow(v[1], 2) + pow(v[2], 2));

factor=2;
module carveout(points, n) {
  if (0 != n) {
    assign(center = sumv(points)/len(points)) {
      difference() {
        for (face = ofaces) {
          tetrahedron([center, (points[face[0]] + points[face[1]]) / 2,
                               (points[face[1]] + points[face[2]]) / 2,
                               (points[face[2]] + points[face[0]]) / 2]);
        }
        for (segment = edges) {
          assign(edge = (points[segment[0]] + points[segment[1]]) / 2 - center) {
            assign(b = acos(edge[2] / length(edge)),
                   c = (edge[0] == 0)? sign(edge[1]) * 90: (atan(edge[1] / edge[0]) + ((edge[0] > 0)? 0: 180))) {
              //echo(length(edge), b, c);
              translate(center) rotate([0, b, c]) cylinder(h=length(edge), r=4);
            }
          }
        }
      }
      for (point = points) {
        carveout([(point * (factor - 1) + points[0]) / factor, (point * (factor - 1) + points[1]) / factor, 
                  (point * (factor - 1) + points[2]) / factor, (point * (factor - 1) + points[3]) / factor,
                  (point * (factor - 1) + points[4]) / factor, (point * (factor - 1) + points[5]) / factor], n - 1);
      }
    }
  }
}

module foo(center, size, n) {
  points = [
    center + [l / 2, 0, 0], center + [0, l / 2, 0], center + [0, 0, l / 2],
    center - [l / 2, 0, 0], center - [0, l / 2, 0], center - [0, 0, l / 2],
  ];
  difference() {
  //union() {
    polyhedron(points=points, faces=ofaces, convexity=1);
    carveout(points, n);
  }
}

//a=[[0,0], [1,1]];
//echo(a);
//echo(a+[[2,2],[3,3]]);

//l = 90;
//l=128; scale(1);
//l=256; scale(.5);
//l=512; scale(.25);
//l=1024; scale(.125);
l=2048; scale(.0625)
//scale(.5) foo([0, 0, 0], l, 5);  // this generates the problem file; takes long time to render :(
scale(.5) foo([0, 0, 0], l, 2); // this I don't know if it is problem, but renders faster to give an idea about model