How do you make fake arm casts?

Question

Can someone tell me how to make a fake arm cast? I wanna pull a prank on my parents on my birthday. Can someone tell me step by step. Also, I want it to come of really easily but I could put it back on again.

Answer 1

paper mache

Answer 2

plaster of paris...its harder.  but do a layer of paper mache first, or you're screwed hha...loss of skin and hair will ruin your prank.