On Mon, 11 Apr 2011 11:26:15 -0700, Tim Wescott
wrote:

So what do you call molding with styrofoam beads?

EPS (Expanded Poly Styrene) molding.

I looked into setting up a line once, and it was too much hassle-
required a boiler to heat the beads etc., but I think this process
might actually be possible on a table top using your aluminum molds.
Worth looking into. Alternatively maybe some kind of reaction molding
(RIM) that leaves the wheels full of bubbles but with a tough skin.
Getting the materials in sensible quantities for you could be a
challenge.

* AFAIK, just about anything with wheels and a minimum weight calls out
7 grams -- 14 grams for outdoor.