Piston Box designed by Marcel Gillen (invented by Tadao Muroi) and made by Bits & PiecesThe Piston Box puzzle is also known as Internal Combustion or Pandora's Box. This is a heavy metal puzzle for its size, weighing in at 329 grams for all 4 pieces and box frame. Assemblies that require different numbers of steps are possible, making this several puzzles in one!The puzzle was made pre-2000. The pieces and frame have a nice weight and the action is smooth.