At work we use Spring steel, like the bands on shipping crates, and just hit them on a fine grinding wheel at a slight angle,just a hair below 90,you will feel the burr on the back side,for a super quick,very smooth blade use a box cutter blabe and burnish it, just angle the blade at about a 45 and run it across the shank of a router bit or a good smooth screwdriver, two passes.It takes a little