The suit is made from a very hard Urethane Plastic. It isn’t one of those cheaply casted vacuumformed suits.

Via: Ebay

Via

This is a hand-painted custom of the Transformers Movie Deluxe Optimus Prime in Protoform action figure. This figure was a bit boring in its original form, but I saw a lot of potential in it, as it was really poseable and well sculpted.