Viktor Genel has come up with several very cool puzzle designs and I think his coordinate motion puzzle called "ReCube" is one of the best. He has given me permission to reproduce it here.
The puzzle consists of three identical pieces that slide together simultaneously to form a cube. It's not hard but it is, I think, very elegant. Please note that you need three of the pieces shown here to make a complete puzzle.
Viktor has a website and for more information about ReCube, see his blog posts:
Pyrigan & Company
For the most part, I design and make high tolerance mechanical puzzles in aluminum, brass, and steel. You can read about them on my website (https://pyrigan.com). But I also enjoy solving other people's puzzles and when I find one that I think will come out reasonably well when 3D printed, I create an .STL file and try it out. If it's a success and the designer gives me permission, I'll add the puzzle here.