Here is a rough cut at the middle of the missing link. Perhaps it is the very essence of the missing link. It starts with the cube expanded to the haptihedron and inverted into the Vector Equilibrium (VE).
The following description helps to picture the missing link. Consider a VE built of closely packed spheres. Start with a single sphere. Pack 12 spheres tightly around the core. Then add another layer of spheres nesting in the gaps between spheres in the first layer. Add another layer of spheres -- 92 of them. The form is a VE. The 92 spheres move for some reason and in some way and come to rest as an icosahedron. This can happen if the core sphere is removed or collapsed. The same number of spheres remain in the outer shell, arranged slightly differently. Buckminster Fuller called this proces energy-valve functions, a jitterbug. See section 460 of Synergetics 2.
To complete the link, invert the icosahedron into the dodecahedron and add them together. Now you have an icosidodecahedron, or simply, an EIE.
If you don't see an animation, your QuickTime 3 or movie plug-in is not working. Not to worry, later I'll provide an animated graphic and much much more on this topic.
One aspect of the transformation is that the movment seems to include spirals, both ways. That is some of the spheres move in a clockwise path and others move counterclockwise. Isn't that something?!
See this movie doubled, two on a page. Transition index.