This puzzle is perfect for folks who like things neat and tidy and everything in its proper place. It's got two hinged "rulers" which satisfyingly slot into 42 little holes in the board - once you solve the puzzle and fit them both into the limited space.
If you're looking for a fun physical activity to stimulate your brain, this puzzle from the mind of Jean Claude Constantin may just be the answer. Made with wood and acrylic, it ships in a plywood box that makes for a striking presentation if you're gifting it to someone. Just don't be surprised if they're cursing you the next day.