Flexi-Cubus - build your own working model by UGears
Flexi-Cubus is a mechanical anti stress puzzle in the form of a steampunk skeleton cube made out of eight joint-connected spheres. The Flexi-Cubus is designed as a means to improve your attention and focus on a task you are working on.
Assembled Size: 115 x 60 x 28 mm Package size: 278 x 185 x 5 mm Number of parts: 144
This was a present for my 17yr old brother. He found it fiddly, especially when he went wrong, but seemed to properly enjoy himself. Great gift, with decent instructions that make sense (helps to follow them!). Would definitely recommend :)