hi there.i found something in one of Sansweet's books. i hope this will help out:

   When Kenner decided to make a gold C-3PO action figure carrying case,they wanted to see how much packaging it needed to protect the finish in the shipping process. So they took about 100 of the black plastic Darth Vader cases,vacuum metalized them in a gold finish,and shipped them to and from Kenner headquarters.(i would love to have one of them!) I have never seen a white one.it could be a prototype.