I have a friend who buys plaster bandages and uses them to make face masks. She just gets the strips that contain the powder, wets them, and places them on a person's face to harden.
She used my face as a model once, and it felt really weird. Just in those few minutes while I was waiting for the mask to harden, my face itched terribly, and it felt really hot.
Once it was ready, she just peeled it off my face in one piece. It's pretty amazing that you can make a full face mask using a bunch of little bandages.