I used to use a leather pad but cut my left index finger a couple of years ago and it hurt too bad to bend that tight. I now use a rubber pad, some sort of conveyor material I think, and it seems to work pretty good. I have slot cut in one side like you mentioned, but when I notch I use the bottom of it w/o a notch. That's what works for me. I got the material from a great guy here on PA flintknapping page. dp