Tom,
My wife was watching HGTV last night. I caught a very small bit of a show where they were using epoxy grout in an unorthodox application. It was one of those shows where either they are designing on a budget or preparing a house for sale, I'm not sure.
Instead of using it as a grout they were putting a skim coat on a formica countertop to give it a stone look. The troweled it smooth and then sanded it down after it cured.
You can never tell what these things really look like on TV but the effect was not nearly as rubbery as I would have thought.
It might work pretty well for your application.
-----
Current snakes:
0.0.1 Gonyosoma oxycephala - Java locale (green)
2.2 Gonyosoma janseni - Seleyar locale (all black)