This is what the C-3PO minifigure from The Force Awakens themed-LEGO looks like. (Source: BrickFanatics.) As you can see, our favorite bot has a red arm this time around. StarWars. The following from StarWars.com:
Fans of the galaxy’s greatest protocol droid have noticed that in Star Wars: The Force Awakens, C-3PO has a new red arm. In a special one-shot from Marvel, we’ll learn just how and why he got it.