I heard about a similar incident in the Santa Clara county jail. In that case, the inmate, ironically facing a federal counterfeiting currency charge, managed to make a skeleton key to the jail by cutting plastic from a jail-supplied Rubbermaid bin that was supposed to be used for storing personal property. The inmate got the general shape of the key by looking at it as guards passed by, then perfected it over a period of weeks by sticking it in the lock and attempting to turn it. The lock made marks on the plastic where the teeth were supposed to go. The inmate was caught and all plastic bins removed from the jail after the key was finally good enough to open the lock, which set off an alarm.