I like how Hanayama Puzzles says its tiny new CAKE Cast Metal Puzzle is recommended for ages 12 to 105 years, but "A few bright children between 8 to 11 years" might also be able to solve it. In other words, parents out there who think your kids are the smartest and best: Game. On.
Hanayama Puzzles of Japan has been making these nifty cast metal puzzles for 25 or so years now. CAKE was released for 2017 and, at 1.6" in diameter and 0.75" thick, I think it fits right in amidst the current fidget toy and spinner fad. CAKE, for those of you who don't have a sweet tooth, is so named because it looks like a round cake, with a big quarter-slice cut out. Within gap from the removed slice are 3 internal discs with interlocking channels, the overall aesthetic of which looks like CAKE has had its cut slices shoved back inside it.
To have your CAKE and conquer it too, you have to remove the 3 internal discs.
And then finagle them back inside.
Called a "disentanglement brain teaser," CAKE has a Level 4 difficulty rating (out of 6). Hanayama Puzzles notes, repeatedly, that their puzzles require "NO FORCE" to solve.