How to Make a Fake Arm Cast. A fake arm cast can be useful in a number of situations. Maybe you want to play a prank on your friend, or maybe you need a cast for a costume. You can use a simple method, such as making a cast out of toilet.
This is one of my favorite tricks to deal with a cast- use a foam ball and stab it with your favorite pen. The bulk of the ball allows you to control the pen when you cannot reach around it with your finger tips!