This treasure chest contains some extremely rare and valuable Meccano parts, so it is well worth trying to get it open. The lid of the chest is locked shut and can be easily opened by guessing a combination — or so it first appears!
The solution is in fact to spin the whole chest around briskly a few times. The combination dial on the front is a red herring! The centrifugal force pushes two locking pins inside the chest out of the way, allowing the lid to open.
To lock the lid, the user must first gently push the two locking pins inside the chest outwards, before closing the lid. Finally, they must press the two concealed buttons (axle rods hiding amongst the bolts!) on each side of the chest to move the locking pins back into the locked position.
This model was inspired by magician Chris Ramsay’s puzzle box reviews on YouTube, where he frequently finds spinning a box will unlock part of the puzzle.