The locking mechanism on the sliding door for my balcony is crappy and it sometimes locks people out on the balcony if they aren't careful. One idea I had to make the door safer was to just store a key in the lock. But it would be better if I could re-key the lock using some product that was designed for this application: I'm envisioning a barrel that fits inside standard locks, but doesn't actually have pins or a key hole, and just has a knob or thumb screw.
How can I re-key a lock so it is always openable without needing a key?