This tool/jig was made to help when you are welding on a bushing to attach a pulley. The tool help get the bushing aligned. You want the pulley to be in the plane determined by the cable. The steel rods will point in the direction of the cable on both sides of the pulley. The ends of the bushing need to be square. For the Piper that I was working on here the pulley will be held on with a 5/16" bolt. However, use a smaller bolt, 1/4", when you are tacking the bushing onto the airframe. A 5/16" bolt would be difficult to remove after welding. After the bushing is welded on, it will be reamed to 5/16".
For the rods in my jig I used 1/8" spring steel. They are soldered to the steel parts which are 1/8" thick.