This is a Leonardo-stylecompound of two tetrahedra (Stella Octangula). A
Leonardo-style model is hollow, consisting only of solid struts along the edges
of a polyhedron. It is also a partial stellation of the
cubitruncated cuboctahedron (partial because
the octagonal face planes are not represented). This model is provided in
Great Stella's Polyhedron Library
(Stella Library → Leonardo-style → Leonardo Stella Octangula).
You can also find it in the
MoStella Gold Android app.
Here are the different types of part required.
Put the inside together first.
Cover the inner skeleton with the remaining parts.