A compound of tetrahedra might be:
Compound of two tetrahedra – stellated octahedron Compound of two truncated tetrahedra Compound of three tetrahedra Compound of four tetrahedra Compound of five tetrahedra Compound of six tetrahedra Compound of six tetrahedra with rotational freedom Compound of ten tetrahedra Compound of ten truncated tetrahedra Compound of twelve tetrahedra with rotational freedom