I love the Kobayashi Fidget Cube! It’s a clever, 3D-printable fidget. The most amazing thing about it is that no assembly is required. Through the magic of 3D printing, all the joints are printed “in place”. I’ve printed many of these fidgets, and the one objection I have is that 3D printers can create sharp-feeling 90-degree angles, and this design has many of them. The cube is intended to be manipulated by a person’s hand, and those sharp edges can be annoying.
I contacted the original designer and asked if I could get a copy of his design’s “solid model” so that I could add a small chamfer (a 45-deg!ree cut) to all the sharp edges. He was generous enough to point me to his work on Tinkercad. Tinkercad can’t add chamfers, but it can send the model to Fusion 360, which can. It was tedious, but I was able to add a 0.75 mm chamfer to all external edges, and this design is the result. This “remixed” design has a much softer and comfortable feel while it’s being manipulated.
After printing, you’ll need to free up the joints by moving them back and forth a few times.
You can download the STL and/or Fusion 360 solid model files here.
Printing the cube with 15% infill and 0.2 mm layer height takes around four hours. I suspect that the cube will feel much smoother if you print it with a 0.1 or 0.15 mm layer height. Don’t print with supports even if your slicer says you need them.