Become a professional locksmith constructing a giant padlock with visible mechanism. The visible cylindrical mechanism shows the way that a key opens a lock.
When you close the padlock, the safety barbell catches in the slot of the short edge of the neck, locking it in place. Without the key in the lock, the three locating pins are associated with the three rings, preventing the body of the lock from rotating. When you insert your key, the teeth of the key, push the pins out, so that their edges align with the outer edges of the body of the lock. This rids the body of the lock, so you can turn it with the key. The rotation of the lock, pulls back the safety bar, releasing the neck in the shape of a U, which is then pushed upwards by its strings.
Instructions in English..
Also required, but not included in the package: a small phillips-head screwdriver.