Hänglåsfickpussel

I bought this for my desk and it's become a bit of an addiction. Getting the four pieces apart looks simple until you actually try it, and the metal has a nice weight in the hand.

The four pieces wiggle and rotate so smoothly that I figured it out in minutes, then spent another twenty trying to get them apart again. It's a great little fidget for my pocket, though I have to be careful not to lose a piece on the couch.

I fiddled with this thing on a flight and it took me almost the whole trip to figure out how the four pieces come apart. The weight of the metal feels great in your hand, and the solution is clever without being cheap.