This is a Serpinski tetrahedron as discussed in my blog
. It was created via OpenSCAD generated from my polyhedra generator
with the spacefill form and a recursion depth is 3.
To get this printable I had to increase the scaling between levels to 0.54 from 0.5 for the ideal shape. This object is in unpolished alumide and looks very sharp - almost dangerous - well you wouldn't want to sit on it.