A wire frame octahedron with 100 cubic cm "displacement" (enclosed volume). Most sets of Platonic solids are based on a constant edge length, these all have the same volume. The struts have a 3mm round cross section. The vertices are 3.6mm spheres. Try spinning it. Of the five Platonic solids, the octahedron makes the best top.
This model is large, about the size of a tennis ball. It makes a nice desk model or Christmas ornament. The edge length is nearly 2.5 inches or 6 cm.