Lauren, Thanks!! And thanks for the encouragement!!
I have updated the "How specifically will these materials be incorporated into your solution?" section with what is hopefully a better description.
For prototyping I would probably try and work with a vendor that already produces the flooring created with Nike Grind material. I would ask for slabs of the material and then carve them to created version of the various ideas I have.
For testing I would probably try something at home first...like a mini ramp to help me get materials in and out of my garage (which has a 4" concrete sill) with a dolly. If that does work out...I would probably next try it at a local senior center or park where I have observed a small elevation change being a hindrance for access. I am not sure what the step by step process would be because I have never done anything like this before. I would probably have to work with someone who is familiar with the material and how to use it as part of a composite and bind it into a shape.
I am guessing that one of the vendors currently creating items might be interested in a collaboration. Its funny, the more I think about the idea...the more I am gravitating to the mini-ramps and speed bumps/hump and away from my original idea of filling the traffic barrels with rubber grind material.