This is a simple puzzle, similar to a Rubik's cube, that almost anyone should be able to solve. When twisted, it changes it's shape, meaning that stickers are not required. It should also be relatively easy to print.
55mm x 55mm x 20mm
You will need to print one of each of the files.
For tutorials about 3d design and engineering, visit my website at https://www.constrain3d.wordpress.com
This model will print entirely without supports. I printed it in PLA plastic.
You might need to lightly sand a few of the pieces, depending on your printer. just sand them until they move freely, do not overdo it. The video below (also at top of page) will show how to assemble the puzzle.