I made key extractors, for getting broken keys out of a locks, with busted hacksaw blades.
Use a piece of hacksaw blade about 2 - 2 1\2 inches long and grind it down. Leave it wide at one end for a "handle", and grind down the other end for about an inch till its skinny enough to slide into the lock above the busted key. The hacksaw teeth have to be pointing backwards. Line them up with the teeth on the key and flick back. It usually comes out after a few tries.
