Here is the aluminum "angle bar" I used. It's easy to cut and drill. The size I picked out is 1/16" X 1/2" X 3/4" and the sides are just short of 7". The notch cut on the angle bar is about 2" in from the front (the length of your servo from front to back mounts). Your cross pieces can be any length, but I made mine the size of my IC PCB (standard IC PCB from Radio Shack).
Backup circuit (chirper)