Each year, the International Puzzle Party (IPP) is held somewhere around the world. One of its revered traditions is the day-long Edward Hordern Puzzle Exchange, in which participants bring copies of a previously unproduced puzzle to exchange with all the other participants.  To participate, a puzzle must first be submitted for design review and evaluated for quality and originality. If approved, the exchanger must produce enough copies for all the other exchangers. On the day of the exchange, ...