We found a bunch of old prototype VEX Wheel-Legs. It is interesting to see the evolution of the product:
http://jvengineering.blogspot.com/2010/08/behind-scenes-vex-wheel-leg-evolution.html
Design is iterative.
I like that they began looking more like legs with feet and then evolved. I know i have said it before but i really like the inside look that you have given us through your blog.
~DK