A three-dimensional maze. Put the ball in, and see if you can get it out again! Designed for use with a 5/16th inch (7.93mm) ball bearing (not included!)It makes fairly easily in PLA with the standard 1 shell + 10% fill. If you compile the included C++ program, it will create a new random maze, which you can cut-paste into the SCAD file. If you don't like the way the ball can be put in the entrance but can't come out again, set want_valve = 0; in the SCAD.