Lock smithing is a skill I picked up some years back- and one of the most useful skills to have is the ability to quietly make a key for something like a pistol safe when you need to get into it without breaking in or making too much noise,
This technique was detailed in a CIA manual that I had access too some time ago and maintained that it was quicker in some instances than picking.
Firstly the technique is only useful when opening locks with Lever tumblers which are still the most widely used, as they are cheap and quite secure.
What is required to use this method?
1. A small pair vice-grip of pliers to hold the blank (think vice grip Leatherman tool)
2. A small set of files- just one will do, but more is better
3. A candle and/or a box of matches(any source of soot)
4. A few key blanks or bits of metal that can serve as keys that fit in the key way
the method …
1. Blacken the blank key with the candle or matches where the key will meet the levers.
2. Insert the key carefully into the lock so as not to disturb the soot
3. turn the blank in the lock
4. remove it carefully
5. inspect the soot for markings indicating how many levers, and how what angle the levers touched the key blank
6. file down a little for each lever and repeat from 1 to 5 until all levers scrape the key on top as apposed to the side
7. you should now have a working key for this lock
For tumbler style locks make a “bump key” which you can use Google to find loads of instruction on the web