I understand if you feel the need to punch my face for the pun in the title. I'm sorry, I had the compulsion and just couldn't fight it.
Anyhow, step two: making molds and casting soles. Knowing that these soles would be the first stop on an iterative design journey, I made them happen as quickly and cheaply as possible. So long as they could shed light on the unknowns in our quest for better athletic footwear, then they were doing what we needed.
And what makes quick, cheap molds for prototyping?
Scrap wood and homemade play-doh, that's what.
Here you can see clear rubber left over from another project that I used in the plywood and play-doh mold, breaking it upon removal.