A thin drawer is removed from an equally thin wooden cover. On one end of the drawer a quarter is found in a recess. The quarter is dumped out and the drawer is shown cleanly on both sides…there’s only the empty recess on one side. The drawer is slid back into the cover. When the drawer is slid out again, there is another quarter in the recess! It’s dumped out and placed in the performer’s pocket … and the effect & production of quarters can be repeated continuously!
This would puzzle many magicians. There are no coins hidden in the cover at any time. Because of how the slide is handled and openly shown at the start, it just seems impossible. Not self-working, but not difficult either.