I'm working on two shields right now, both from the popular sled bases. One plastic, one steel. I've been putting off the steel one because I'm terrified of cutting off the rim. I don't like the idea of losing any of the diameter, and I'm a huge perfectionist, so pretty sure any cut I make with my jig won't be good enough, and i'd then always consider it a failure. However, just read about someone who filled the gap instead of taking off the rim. Has anyone here done that? Any tips?