Daryl Pelfrey... All you need is a $15 jewelers saw and some blades, along with a few files. You just draw on the brass and saw, or attach a paper pattern and saw. Make sure you get 1/8th thick stock, unless you are going for a flush side plate. Regardless, use the files to clean up the edges and chamfer them, as you will have to do anyway with a commercial side plate. You can always copy a side plate too, easier done if you have a TOW catalog with exact size prints.
Matt