A portable illusion with a twist
A box is introduced and the front door is opened. An assistant places their arm into the box and grabs hold of the bar at the end. The door is closed. The magician now proceeds to rotate the end of the box around and around - twisting the arm of the assistant. When the front door is opened again, the bare arm can be seen to be all twisted. Ouch! The door is closed and the end of the box is rotated in the opposite direction to return the arm back to normal.
What is great about this illusion is that the hand is always holding on to the bar and you can see it each time the front of the box comes around into view. The illusion is very strong.