I have used Rit Dye and iDye Poly for wheels and car parts, and 2 weeks ago i tried both on my Spektrum Tx (black and red).

Don't know if it was the type of plastic used by Spektrum or the silver coating they use, but it did'nt take.

I also tried to dye lexan with both types of dye, that would have openned up several interesting uses, but it didn't take to lexan either.

Good idea though.