You have a locked object that you really want to open, but can't find the key. (Or worse yet, someone took the key and won't give it to you). Luckily, locksmith mob sells clay to make imprints of the lock, and makes temporary keys for you from imprints brought to him.

So: Player A buys some imprint clay from the locksmith. He is out wandering and sees Player B hiding behind a locked door. He makes an imprint of the lock and returns to the locksmith.

The locksmith either a) understands the design and creates a key, price dependant on the level of the lock (pick lock rules apply)

or b) Can't figure out what the heck is up with the design or the imprint and can't make a key for the lock.

If player A gets a temporary key, they can use it a few times (2? 3) on the door before it breaks (it's only temporary after all), but at least enough time to get in the door and go after Player B.