I can't say wether this backer piece of metal is the one that originally came with Vader, but if it's not chances are it looked very similar.
Apr 25, 2017
DARTH VADER METAL PIN
A very basic metal pin of Darth Vader from the waist up. Not too shabby looking for a bootleg/knock-off kind of thing. I saw an R2-D2 pin like this, too, although it was an image of the entire droid. Off hand, I'm not aware of any others from this set.