Aluminium parts

Hi,
firstable i would like to tell you that i'm not english so, sorry for my bad english, try to understand, i'm doing my bests.
I'm trying to understand if aluminium parts do exist, not for the body, but to repleace plastic parts like the cover of the radio RX. If yes, where can I buy them (on the internet)? :?: :!:
Tanks a lot, byez.