Next I cut the opening in the bottom of the wing sheeting to frame the servo mount tray. Picture is a little fuzzy but I think you can see what I did. The opening in the wing sheeting is framed with lite ply all around and then backed to the servo mount tray with 1/4" x 1/4" balsa shaped to fit. Then I added sheeting balsa strips from the servo tray plywood to the wing sheeting on the inside, then glued in the tray doublers as well on the back.