Yeah 90d is like hard hat plastic. I was thinking more along the lines of a 70a which would be a bit more rigid than tire rubber. More along the lines of the hard soles on dress shoes. That would be a D hardness in the teens tough. Three gallon of that is about 200 freedom bucks and is a 1:1 by weight so it's difficult to mess up.
I'm just speaking from what I know about the pourable urethanes. I know nothing about water cutting. I wonder how many sets could be had out of three gallons though.
