Satifiable Puzzle

This CAD model was designed by Oskar van Deventer, copyright (c), 29 December 2024. Concept: 22 June 1984

Satisfiable Puzzle has ten buttons. The goal is to push seven buttons down. However, when you push a button down other button(s) may pop up. Magnets keep the buttons up or down. Seven lengths of ball chain engage with the buttons. Three buttons rest on each length of ball chain. The length is chosen such that when two of the three are pushed down, the third one pops up. It is easy to push five or even six buttons down, but the seventh has a unique solution. Once you have solved the puzzle, you can randomly swap the buttons and try again. It is a very tactile and pleasing puzzle.

The puzzle was named after the Boolean satisfiability problem (https://en.wikipedia.org/wiki/Boolean_satisfiability_problem). This is a classic problem, where the challenge is to find the binary input values for which a given Boolean expression results in "true". The problem is NP-complete, which means that it is hard to solve, but easy to verify that a solution was found. This is also true for the puzzle, where one can easily verify that seven buttons are down.

These are the additional (non-3D-printed) parts for this puzzle.
-A piece of commercial-of-the-shelf ball chain. I measured the balls to have a diameter of 2.2 millimeter, and a spacing of 3.08 millimeter.
-Twenty (or fourty) small cylinder magnets with 3-mm diameter and 2-mm thickness: https://www.supermagnete.de/eng/disc-magnets-neodymium/disc-magnet-3mm-2mm_S-03-02-N.

Here are some links about this design.
https://www.youtube.com/watch?v=BFxGQi9P6fM
https://i.materialise.com/en/shop/item/satisfiable-puzzle
https://i.materialise.com/forum/t/satisfiable-puzzle-by-oskar/3851
https://twistypuzzles.com/forum/viewtopic.php?t=40033

Feel free to 3D-print an extra sample to give to a friend, as long as you mention the designer and don't charge money.

If you are planning to sell some samples, then please contact me for a license agreement. The royalty fee is 10% of your selling price.

Please do not upload the design to a commercial service, or redistribute the design in any way other than linking to the YouTube video: https://www.youtube.com/watch?v=BFxGQi9P6fM

Enjoy!

Oskar
1 March 2025

Contact: 
https://oskarvandeventer.nl/index_contact.php?subject=Print%20It%20Yourself


