Well, as we saw last week, I've been learning Autodesk Inventor and I thought a good challenge would be to make some polyhedra, namely the Platonic Solids. All of these have a neat dual property that if you connect edges between the face centers of any regular polyhedron, you get a dual. This turns out nicely symmetrical: last week we saw the cube-octohedron dual, this week I got to the more complicated icosahedron and dodecahedron, each with their duals trapped inside. Because these can't easily be fabricated by anyconventionl method, it's a good way to show off the capabilities of 3-D printing.

Here's a dual pair of duals. On the left: A 12-sided dodecahedron with its dual icosahedron (the 20-sided polyhedron familiar as the D-20 from gaming) captured inside. On the right, its dual: an icosahedron with its dual dodecahedron captured inside.