The puzzle was designed by Geoge Hart and published in one of
his puzzle pages: http://georgehart.com/Puzzles/CubePuzzle
It consists of two identical pieces that match to form a cube
by turning one piece in respect to the other. The two pieces are
separated by cutting the cube by a helicoid surface.
This code models a puzzle cube very similar to the Hart's one
but it is based just on his description and images and may be
a bit different.
The hardest part of the coding have been to deal with a constant gap between the pieces. I am in debt to Rudolf Huttary (http://www.thingiverse.com/Parkinbot/about) for his clever solution to the computation of the helicoid offset.
The stl files were generated for a 50mm cube. The code has some customizable parameters so you can create your own variant.
There is no special printing requirements. The only concern may be the gap between the pieces which is customizable. The stl files where generated with a gap of 0.2mm. Some trial and error may be needed.
Another possibility is to print both pieces already assembled. I have not tried that but I would suggest a bigger gap because there is no way to separate them after printing with an utility knife.
The file CubeScrewAssembling.stl was not intended to be printed. It may help the understanding of the piece match by using the Thingiview.
I would like to thank Helena Leitão who have printed the model for me in PLA.
I had to file the pieces a bit to get a good fit and smooth movements. Do not file too much because they will tend to be loosed with the use.