Napping flint is an art. You start with a chunk of obsidian. Then you bust it into smaller pieces known as flakes (flint). The flakes are then "napped" into other items. (Broadheads are popular for traditionalists)

This is a broad overview...and there's obviously a lot more to it, and I'm no expert...but a guy I work with naps flint, and he is trying to get me into it. He actually killed a deer last year in Ohio with a home-made longbow, hand made ash arrows with turkey feathers from a bird he killed, and flint broadheads.