My home made lock picks for single bit locks. Made out of plain old steel banding from packing crates. I just cut it to the length I wanted with tin snips and went over to the bench grinder and ground in a few grooves.
You can make a fine tension wrench from the tines of a street-sweeper brush. The Pelican machines you see cleaning the curbs and gutters use steel tines on their rotating brushes and every now and again they lose one.
This little set comes in handy for those "lost" coin door keys which can prevent inspection during a prospective deal.