i'm planning to build a sleek headlight conversion similarly to this Corvette. and would plastic melt?
You can't legally build your own headlights if you plan on ever driving on the street. Haven't you notice on all the custom car and motorcycle shows they don't build headlights? They will build enclosures, they will customize mounts, they will design fenders, but they don't build headlights, because they would have to go through an expensive DOT approval process for each and every one of them. Now that mounting and enclosure in the picture could very well be custom made, however the headlights themselves aren't. Any plastic lens you use has to have no imperfections, or it will distort the light, making it harder for you to see, and blinding oncoming drivers. I suggest you go to a custom lighting supplier (not eBay, few lights on there are really approved) and get a proper kit, likely cost you $600 or more per light for an approved, quality set.
Since you're building your own, I'm assuming you don't have access to a glass manufacturing furnace, so I would suggest 22 gauge or thinner plexiglass, preferably high strength or high temperature. however plexiglass is easily scratched, and the best would be to just buy the headlights with glass. Unless you have a glass furnace there isn't really any glass out there that can be shaped, and glass only come flat.
