The top three photos are the existing panels. The remainder are the cutting and fitting of the panels. Ran out of time tonight. Will cut the window holes tomorrow. 

I added a photo at the end showing the almost completed horn assembly. 

Old on top of new. Measuring for new panels on new plywood. Will cut out, stain, and install. 

They keep dirt out of the bushings for the rudder, elevator, and ailerons.