This is a lockable box I designed in Tinkercad. The locking mechanism is not the best, but takes 5 minutes or so for the average adult to pick it, and it should keep most young kids out. This is the way that the number system works: Large square is 1, circle to the right is 2, small square to the right is 3, and so on. Oh and maybe you will want to print the barrels slightly scaled down to prevent sanding. The idea of how it should look when finished is shown in plc # 1. Assembly directions are in the misc. notes section.