Thanks Jon
I have two methods.
One I use band saw with scrap wood for guide and stop, then widen as needed to get inserts to fit. Sand paper or two hacksaw blades taped together. I cut my inserts as close to the width of my saw blade as I can. Trim up inserts when dry, my string groves are cut on band saw again and widen using 3 taped hacksaw blades. Then shape nocks with small file or spindle sander. Sand smooth to protect string.
Two I also have nifty nocker from Raptor archerey it is the older model and does not work on my 3/8 shafts but the newer version I believe does. He is sponsor here you can see video on web site.
Lots of ways to do self nocks. Good luck.