I had a nice piece of aluminum angle that I had from a track on my observatory sliding roof that I had froma rebuild last summer. I knew I kept this for something good (no, not "hoarding").
I used that as a support for the rudder trailing edge. I clamped it down and drilled a few #40 holes thorugh the skin to the aluminum beam. Then held in with clekos to keep it lined up, then drilled all the way down the length of it.
Filled all the holes with clekos, and I have a very straight and flat edge ready for the glueing of the trailing edge wedge. That's next in this process.
