Used my EDC01 to try and troubleshoot a locker at work this afternoon. The chick got the key to locker A, then shoved it in all ignorance in the lock of cabinet B, and couldn't get it out. If my limited knowledge of locksmithing is worth any, she got one of the pins to drop behind the bitting of the key and trap it in place.
No dice. Paper, pressed plastic, a staple, even a strip of aluminium soda can were no help, either because they were too thick to fit the gap or weren't stiff enough to push the pins back. Tried for half an hour and just couldn't.
The library's gonna call a professional locksmith now to solve the issue, at her expense, and no matter what he has to do, it's not gonna be anywhere near dirt cheap. As my grandma always said: pay attention to what you're doing.