I don't know if you remember the mouse trap board game. For class I got to model and animate the hole game using just dynamics. I'm having problem doing the rubber band effect. The crank turns around and moves the stop sign and streches the rubber band back. When the crank passes by the stop sign shoots back with the rubber band going back to its postion and hits the boot.

I've tried about everything I could think of. Can someone help if they can.