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. It was purchased from H & R Magic Books at the Magic Collectors’ Association Weekend, Schaumburg, 1996. It came in a red draw string bag with ‘Sandfield Joint Puzzle’ 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.