Jelly - inside - visor would be a good application - since fiberglassing inside that hollow visor is a pain, or nearly impossible to get matting in properly, using jelly would just fill it and wouldn't be as heavy.
Then again liquid plastics are seeming more and more reasonable for this sort of stuff, fiberglass itself is such a messy, hazardous and dangerous process.
I say both because it's dangerous for the person using it, and hazardous for anyone breathing the fumes near by.