pretty much use the same materials as you have done on the metal ones. Removing the glued on parts takes a little care, but is fairly easy to do. If you strip the paint down to the resin then you'll just have to be more careful with what you select to use and length of time in the stripper. Though you can probably get away with not stripping at all. Do the modifications, lightly sand and prime and then paint again. Happy to give more info if you want to call and talk about it, please feel free to call me.