I'm sure someone you know who paints cars for a living can paint it for you. Or any paintshop can do it for easy cash just give them instructions which they should paint or not. or you can take it to an R/C shop, those that paint r/c cars and scale models. they can help too.

If it's any help lol I just painted my otterbox case hehe, someday i will also have someone paint the actual casing