Ordinary Banana

You can get sheets of actual Vibram sole rubber (for making sandals). Wonder if seeing soles on would be practical?

I've thought about it - going to try the silicone caulk thing because it has to be kind of 3d not flat, also hard to sew

Hmm, yes! I wonder if you can find something that’s more abrasion resistant. Hmm, google thinks so! https://www.google.com/search?q=abrasion+resistant+liquid+rubber …

good search terms! hmm I hadn't thought about marine products but that makes sense

“abrasive resistant coating for truck bed liners” sounds pretty butch

store ones don't fit my feet. Have notes on making my own: just dipping it in PlastiDip. Basically liquid rubber

theoretically you could later in harder bits of plastic and some toughening agents like fine gritty sand.