To make an icosahedron out of Sierpinsky tetrahedrons is difficult because regular tetrahedra can't tile in space.
The dihedral angle of a tetrahedron is ~70.53. So the first step would be to make tetra's with 72'angles (360/5) and to tile them into two sets of five tetrahedra to form the top and bottom of the icosahedron, and then i would have to fill the middle area with 10 tetrahedra.
What is the easiest way to roughly make an icosahedron from tetrahedra? what are the dimensions of the tetrahedra involved, are they all the same? ideally it would be possible to see through all the triangles in a line from one end to the other, is it possible?