Unless you just want to waste all your precious range time fooling around cutting patches, repurpose a wornout or broken hole saw of the correct size, and make a butt load of patches in a jiffy. One of these cutters, and a cheap drill press will cut five or six patches per pass with the material folded properly.
You can make one of these in no time. Take your old hole saw, and remove the pilot bit, chuck the hole saw up in your electric drill, and take it over to your bench grinder and grind the teeth off. Now you need to grind a cutting edge where the teeth were. I start with the bench grinder, running the saw held in the electric drill at low speed until I start to get a sharp edge. From there on I use sharpening stones on the outside edge, and a ceramic rod to debur and sharpen the inside of the cutter. That’s it. Good luck.
Hungry Horse