Bring out an elegant walnut box with holes in both the lid and base. The interior is just large enough to hold a single playing card. When the card is inserted, it will block all passage through the holes. A gleaming steel ball-bearing is also shown. After all the items have been thoroughly examined, a freely selected playing card is placed inside the box. The lid is put in place, and the ball bearing placed on top of the box. Tilt the box from side to side until the steel ball drops into the hole in the lid. The ball continues right through the card and out the bottom of the box. An amazing penetration.