My son-in law asked me if we could make a “Scrad & Charlie” costume where he could operate the “second head”. I made a fake arm of foam and nylon stocking, attached it to a shirt with an open back. I made the MJ zipper jacket/vest but used edging material vice zippers to keep the cost down. I cut a hole in the back and attached a backpack for his real arm and the puppet head.
I made the head from foam and stocking to match his face (as best as I could). He wears the whole thing with his right arm thru the backpack, operating the head.
total cost.. $25. ( that’s not including the 30+man hours).