I took one of my cheap block planes (they're all cheap) and ground it to a radius like Nick shows in the book. It wasn't as hard as I thought it would be. I roughed it out on the grinder, then a large flat file, and finished it off with progressive grits of wet-dry. I was using it as much on the outside of my GL as on the inside. There are so many convex surfaces on the outside I am surprised it ever encloses. Ray