A fascinating 3-d project, with a complex interior and moving parts, all in a single print.
Push the ball past the spring-loaded jaws, it's only about eight correct moves to get it out, can you discover the secret?
What about your patience - maybe you'll smash the cube to recover the ball!
It is designed for 10mm or 3/8" balls, the holes are nominally 11.5mm and the viewing holes 7mm. Balls down to 8mm or 5/16" will work.
The correct orientation for printing is with the bigger entry/exit hole on top. After printing, clean out the hairs and imperfections with a sharp screwdriver.
I used PLA, if you want to change the scale or material, print the small test model to check the jaws and hole size.
It's actually quite easy, the maze could be much more difficult. To practice, put the ball in the exit hole and learn in small stages.
If you really have to cheat, study the inverted holes model. Or watch the video, http://youtu.be/AvnNPD1WQfs