Wednesday, May 20, 2020

Discretely Exchanging Puzzles - IPP Burr

IPP Burr by Noah PrettymanOnce a year, hardcore puzzle collectors from around the world extract themselves from their daily lives and converge on an unpublicized location to collectively participate in multiple puzzle related activities.  This event serves as an incubator for the puzzle cognoscenti to spawn new puzzle design ideas into the world.  One of these incubating activities is the esteemed historic puzzle exchange, which I’ll simply refer to as the E.H. Puzzle Exchange.

The E.H. Puzzle Exchange provides the opportunity for participants to bring multiple copies of a unique puzzle that will be traded with the other participants for one of their puzzles.  The rules for the exchange are as follows:
  • Exchangers become eligible to participate in their second year. Ideally, they have participated in a prior E.H. Puzzle Exchange at least once as an assistant to learn how the process works.
  • The entry must be a new puzzle. This requirement eliminates the possibility of receiving a puzzle that may already be in a collection. It also spawns new puzzle designs into the world to be enjoyed by metagrobologists everywhere.
  • All exchange puzzles must pass a routine design review.
  • Each exchanger must be prepared to have up to 100 copies to exchange with other participants. Many exchangers bring additional copies to sell to people not participating in the E.H. Puzzle Exchange.
  • Each participant is allowed one assistant to help with exchanging all those puzzles. With up to 100 puzzles to exchange in a single day, an assistant is much appreciated. Participating in the E.H. Puzzle Exchange is a great experience and assistant positions fill up quickly.
The E.H. Puzzle Exchange is conducted in a single large room where each exchanger must locate every other exchanger to complete the exchange.  Some exchanges are very simple, while others can be rather complex rituals.  Exchanges sometimes entail detailed choreography consisting of themes, costumes (both additive and subtractive), props, dancing, singing, and outright buffoonery.  When volunteering as an exchange assistant, it is always a good idea to know something about the exchanger to have an idea what you are getting yourself into.

For each puzzle exchanged, there are 3 main components: the designer, the maker, and the exchanger.  Sometimes the same person fulfills all three components and other times each component may be supported by a different person.  The 2018 E.H. Puzzle Exchange included a puzzle that was made and exchanged by the same person but designed by someone else.  The puzzle was IPP Burr, designed by Noah Prettyman, made by Eric Fuller’s company Cubicdissection, and exchanged by Eric himself.

IPP Burr PiecesAfter the puzzle event, the IPP Burr was released to the general public on Cubicdissection.  The puzzle looks like your typical 6-piece burr, but in addition to the normal 6 pieces, there are 3 encapsulated smaller pieces, each like a little pip nestled in a piece of fruit.  The 6 outer pieces are made from Ash and Wenge and form a checkered pattern on the ends.  The 3 small pieces are made from Spalted Tamerand and spell out IPP, giving the burr its name.  The puzzle was delivered unassembled to maximize the solving pleasure.

This version of the classic burr is quite challenging and Noah has done an excellent job of coming up with something new.  In order to make room inside for the 3 pips, the 6 larger pieces are relatively open (i.e., they have fewer voxels/cubies) and can be put together in multiple ways.  The trick is to discover the configuration that permits the 3 pips to be oriented inside in such a way that the puzzle can be assembled/disassembled. 

My solving process was broken down into several smaller steps.  The first step was to figure out how the outer 6 pieces can be configured to make a space that will hold the 3 pips.  The checkered pattern is useful here for identifying how the pieces could be paired.  There are multiple ways to create the outer shell and it takes some experimentation to discover the correct one.  Yes, there is only 1 solution.  This experimentation was done by using 4 of the 6 outer pieces to make an open shell that could be used to test how the smaller pieces would be inserted.  Once the correct configuration was determined, all that was left was to disassemble the cube while mentally envisioning the last 2 outer pieces included in the puzzle and then assembling it again with the last 2 pieces actually there.  Sounds easy, but it took awhile to discover all the correct orientations.  Some of the moves also require shifting the internal pieces, which is why the puzzle is a little on the loose side.  If it ever became tight, that would be a real problem.

With only a level 5 solution, you would think that this burr would be easy, but the packing component of the solve makes it more difficult than you would expect.  What I did expect was to enjoy this puzzle and I wasn’t disappointed. 


  1. Congrats! Well done!

    My solving process was different. I entered the puzzle into BurrTools (with color constraints) and hit "solve". Then the nightmare began. It turns out that the assembly animation shown by the program is hard to achieve, because gravity was not considered by the software. Nuff said. I am still in recovery.

    1. Thank you George. You made it all happen. Sorry to hear about your traumatic experience. The puzzle has a single solution regardless of color constraints but the end result would certainly look nicer with the 2 contrasting colors. Hope your recovery goes well. I know several puzzlers that spin tops for therapy. You may want to try that :)

    2. I removed the color constraints in BurrTools and it gives me two solutions! However, they can be considered the same because it just swaps two pieces which are identical in shape. They are colored differently, so it is possible to assemble this puzzle so that the final coloring is not symmetrical.

    3. You ended up with 2 solutions because you explicitely created 2 pieces. If you just used one of the pieces and specified that 2 copies should be used when creating the puzzle, you would have ended up with a single solution.

  2. Glad you enjoyed the puzzle! I had a ton of fun designing it and wanted the solve process to be unique as well as difficult. Good to hear that those objectives were met in a satisfactory way :)


    1. It's a great puzzle! Thank you for that one.