Hanayama's Donuts brainteaser features two intertwined ring shapes for you to disentangle. The gleaming rings have a chrome-like finish: one is dark and one is lighter. Your goal is to separate the donuts into four pieces and it's trickier than it looks. Puzzlers suggest trying to imagine the inner structure of each ring. Once you've figured out how to separate the pieces, can you put them back together again? This 1.69'' x 1.69'' x 0.31'' cast metal puzzle designed by Vesa Timonen is considered difficulty level 4 (challenging).