This unassuming 160mm 5-piece puzzle forms a perfect square when assembled correctly. Don’t let the images fool you — without the solution, even the most intelligent adults may give up on this one. Out of the many people of all ages and abilities I’ve tested, only 2 or 3 have been able to solve it on their own (including one particularly precocious elementary schooler). 

Great for stumping your friends, challenging your kids or as a teaching aid about the importance of instructions, creative problem-solving or underestimation. Great for groups and classrooms as well. 
 

printing recommendations: 

1. Printed with a .4mm nozzle at .32mm layer height (4 layers). 
2. Ensure you have great bed adhesion, since this print is rather thin.