Hi, I am new to the forum and mainly a knifemaker getting into making my own custom sheaths. And usually abide by the axiom "that it is better to keep your mouth shut and be thought a fool, than to open and remove all doubt". Anyway her is my idea...I have found that using templates of my favorite patterns saves me time and improves precision of reproduction. I found using the thin plastic(?) cutting boards (WalMart) make excellent templates. They are easy to cut and very durable. I would make a set for each style and size of strap. Place on strap,scribe and cut with head knife . Mean while save my pennies and buy the punches. Hope this is helpful.
Safe cutting
Dakota