What can I use to fill, seal, and polish out a small crack in my plastic headlight?

there really no way to fix it i build hot rods i have gone through that to i have to bye new ones what kinda bike do u have my lights on my 33 ford roadster are for a Harley Davidson fat boy they were 500 a pace you may be able to pick one up cheep at a swap meet for a 100 bucks