Im not much help, but Im sure if you look around on the net youll see some examples of simple dies that you can just stamp out shapes with, at least might give you some ideas.
I use to use a large washer, which you can sort of grind to a profile you like btw... and hold it against the call, and use scissors to cut up against the washer, cutting the tape to shape. Not perfect but ok.
Im sure with a cnc machine it would be easy to cut something to shape, sharpen it up and use a hammer to stamp out the tape to shape.
Hope that helps ya,
BTW...if you want some pics of my tape cutter, Id be glad to send a few.
Mark