Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:1870525.

Update 21 APR 2019 There is a newer easier-to-print version of this puzzle at https://www.thingiverse.com/thing:3578594.

This puzzle was my entry for the 2011 IPP Puzzle Design competition in Berlin where it was a Jury 1st Prize winner.

"Two open-ended Superstrings with the correct spin can be merged into a super-symmetrical cube." The idea for this puzzle emerged when I was designing shapes based on two interlocked tetrahedra. Inspired by ideas from 'string theory' and 'super-symmetry', I began to search for shapes that were both symmetrical and as similar as possible. The two pieces may look similar but they are very slightly different.