I have always loved Rubik's cubes, but my collection is quite small, seeing as how I spent my hard earned money on an old 3D printer rather than more puzzles. After a lot of work and many hours of designing and printing and redesigning, I have my very first successful twisty puzzle.
One of the things I was looking for when I designed it was simplicity. Gluing things together, having a thousand pieces to print or needing other hardware is something that holds me back from printing many things on thingiverse, so I wanted to make a design that printed in a single piece and did not need any extra work or components to work. I am quite pleased with the design I came up with and I haven't seen anyone make one quite the same way.
It prints with the biggest side on the build plate so no pieces print on top of each other.
Edit: I have now included a version with a bigger gap in between pieces. This should be easier for lots of 3d printers, but will be a looser fitting puzzle so if you can get the original design to work than I would go with that. Enjoy!
Update 2: I Stickered my old puzzle and I Love it!
While these settings work great on my printer, my printer is a very "special" printer in that it doesn't always work perfectly, and various factors (How precise your printer is and whatnot) might need to change. Try it out and let me know what you find.
It might be a bit stiff at first if some of the inside pieces fuse together a bit. Just pick it up and turn. Try all of the different ways and move pieces around. You need to add some coloring system to make it actually solvable. Stickers would work fine, but I just printed it yellow and used some sharpies. They soak into the plastic so it won't wear away very quickly, and if it does, I can always add some more.
Lots and lots of trial and error. I have printed at least 10 different renditions of this. Some of them worked better than the previous designs, and some of them failed miserably. I designed them in Solidworks so if anyone is interested in the files I would be happy to share.