Click the image, which will take you to Massdrop.com. Then, enter PRACTICE in the search box on the Massdrop home page.
THE BRAIN BUSTER PADLOCK CHALLENGE
Do you like locks? Do you like puzzles? Do you like challenges?
If so, this product was made for you. It's also a very very cool gift for anyone who appreciates novelty and rarity. This is a working padlock made of clear acrylic plastic, except for the actual hardware (such as tumblers, activator, etc). You can see everything inside.
The thing is . . . well, it comes to you in pieces. Lots of pieces. You have to put it together, and if you put it together right, it works. If you don't, you can try and try again until you figure it out.
The padlock, being plastic, is not a sufficiently strong lock to serve as heavy protection -- but it does work and it can be used to lock up semi-valuable stuff inside the house, if you really want to put it to boring use.
Comes with instructions, so in the end you can always cheat and pass it on to someone else who likes brain teasers.