I'll add another option for a tough surface, I tend to forget about as it's heavier than glass/carbon/kevlar, West Systems 420 Aluminum Powder. "Abrasion Resistance – Apply undercoats of epoxy modified for abrasion resistance or temporary UV resistance." Much easier to sand than kevlar.

We use it as the top surface on a fiberglass mold, as it forms a very hard coating, less chances of dinging the tooling when removing parts.