Go to any hobby store that sells model airplanes or RC cars. Ask for the spray tint. Use that. Dont go any other crappy way. My tail lights on my fox have been like that for a couple years with no problems and I have done friends' cars for them too, all come out great and last a very long time. If you can spray paint with a can (get runs) practice first then paint your lights that way you dont get them all runny. Also, numerous light coats til you get your desired darkness.