Just take a dremel drum and start going at it. I posted some YouTube videos long ago of where I'd use electrical tape on the edge to guide where I wanted to cut, but I've gained a good eye for it and don't need a guide anymore. If you're comfortable freehanding it you can go head and do that, just keep the return edge at about 1/8" and you'll be in business. Far too often I see people put their Fett armor with a return edge of 1/4 inch and it doesn't look right at all.