Continuing the trend of designing restricted-opening packing puzzles with 4 simple looking pieces, Hajime Katsumoto has provided us with 4 PAC. The box has a single slot opening to permit the pieces to be entered and several poke holes for you to insert your fingers for manipulating the pieces. However, for this packing puzzle, the pieces are round, allowing for new types of rotations within the box. This novelty helped 4 PAC win a Jury Honorable Mention award in the Nob Yoshigahara Puzzle Design Competition in 2021.
This puzzle looks innocuous. After all, we’ve solved several of these 2x2x3 packing puzzles with simple looking pieces. This one looks even easier with the pieces made from cylinders, which support rotations around the cylinder’s axis. When I first saw a photo of this puzzle, my initial reaction was that it could be trivially solved in several ways. Deep down, I knew this would not be the case and was summarily reengaged by a comment on the Mechanical Puzzle Discord server: The solution doesn't use the scoop move. The scoop move? Was this the move that my trivial solutions were based on. Indeed it was. After more thought, this move is obviously (I use the term obviously loosely here since it obviously wasn’t obvious on my first pass) impossible. However, it would have been possible if the top of the box had a thickness of 0 (that’s mm not inches), which the mental construct within my mind indeed had.
Having cleared its reputation of trivialness, I decided to print a copy to solve. Given the nature of this type of puzzle, it’s easy to deduce how the last piece goes in. That only leaves figuring out how to add the first 3 pieces.
|No Scoop 4U