Karakuri Packing

I’ve been wanting to try Karakuri Packing for a while now and I recently had to the opportunity to acquire one from a kind soul on the Mechanical Puzzle Discord (MPD).  Now I can see why others gave it high marks and why it received a Jury Honorable Mention award in the Nob Yoshigahara Puzzle Design Competition at the 40th International Puzzle Party (IPP).  It’s so good! 

Karakuri Packing is a 3D apparent-cube, restricted-opening packing puzzle designed by Yasuhiro Hashimoto.  It consists of 5 pieces that need to be packed within a 3x3x3 box.  The pieces are comprised of 26 voxels leaving 1 voxel unaccounted for.  Oh, what could that mean?  Well, one piece has a dowel sticking out less than a width of a voxel.  But there are also 5 holes drilled into the pieces and 2 additional dowels that have to be packed as well (yes, yes, you can argue that there are really 7 pieces that have to be packed in the box).  Each of the free dowels is just short of 2 voxels.  5 holes and 5 voxels’ worth of dowel.  Coincidence or trap?

To complete the challenge, the box has a 2x3 voxel opening on the top.  For the version that I received, the 1x3 voxel lip on the box is removable which allows the pieces to be packed in an incorrect configuration.  Or you could store it in the correct configuration and be able to dump and scramble the pieces without seeing how they would emerge from the box.

Attempting to determine what novel ideas could be used, I brainstormed some that were not used.  But more importantly, there were moves that I didn’t anticipate.  I was very happy to see these unexpected interactions.

My solve was done in 2 short sittings, The first to convince me that it wasn’t going to be easy.  The second to show me that it wasn’t as difficult as my impression from the prior attempt.  Although there are many assemblies, there are things that reduce the complexity such as the opening restricting the orientation of the pieces and holes needing to be aligned to support the dowels.  Definitely a fun puzzle and I wouldn’t mind seeing other puzzles in this format.

Although I’m very late to the game with Karakuri Packing, others have blogged about it in a more timely fashion like Allard and Kevin.