Slap Happy is based on a toy that most people have played with. We have often seen it as a wooden paddle with a thin, long rubber band attached to it by a simple staple.
Unfortunately, the rubber band would often break off or at the very least become dislodged from the wooden paddle. My design was to have the ball come back to the center of your hand. This was accomplished by the player placing his or her hand under a strap, which was fastened to the plastic hand-shaped unit. I also made the ball much larger and in foam, replacing the small hard rubber ball. If the rubber string came away from the paddle it could be easily replaced by inserting it into the hole and tying a knot.