The Cast Donut, part of the Hanayama Cast Puzzle series, was designed by Japanese designer Vesa Timonen, known for creating elegant and challenging puzzles. Inspired by the smooth, continuous shape of a donut, this puzzle blends aesthetics with a complex mechanism hidden within its minimalist design. The goal is to separate and reassemble two interlocking donut-shaped rings. With a difficulty rating of 4 out of 6 (medium-hard), it stands out in the Huzzle series for its deceptive simplicity and smooth finish . The level of difficulty on a scale of 10 is generally ranked 7/10, challenging but approachable for most puzzlers .