This puzzle was designed by Robert E. Sandfield and crafted by Perry McDaniel. It is a good example of an impossible dovetail joint. This is a type of impossible object, so called because there appears to be no way to separate a dovetail joint which consists of a dovetail on all four sides. To make the puzzle harder, a magnetic lock is inside and it has to be released before the two parts of the puzzle can be separated. Complete with instructions, part of which say ‘Take care not to lose the steel locking pin. It has been trained to take every opportunity to roll under heavy, immovable objects’. The puzzle was purchased from H & R Magic Books at the Magic Collectors’ Association Weekend, Schaumburg, 1996. It came in a blue draw string bag with ‘Sandfield Joint Puzzle 2’ on a piece of wood attached to the string. Because the idea of this puzzle is to take it apart, people interested in mechanical puzzles also classify this as a Take Apart Puzzle.