This thoroughly satisfying kit assembles into a completely transparent safe with a fully functional three-tumbler combination lock on the door. When the combination has been entered correctly, an additional turn of the dial past zero engages the bolt and withdraws it, allowing the door to open. Because all parts of the lock are made of transparent acrylic, you can see the operation of the code tumblers perfectly clearly. The pins that engage between neighboring tumblers are colored acrylic, so they stand out and demonstrate their function in encoding the combination.

This kit includes 252 parts and took us about two hours to complete, though we enjoyed every minute of construction. Measures 12-1/8" x 9-1/8" x 6-3/4" once assembled.