At left is the cover-cover during fabrication. Using some skills left over from my model airplane days, I fabricated it out of basswood (side rails) and balsa (top). Oh, I can hear the moaning now. Basswood? Balsa wood? Yuck you say? Here´s the deal: Both materials are very easy to work with, making a close fit to the cover an easy task. Once you have it all put together, simply treat all the surfaces with a concoction of 30 minute epoxy cut with acetone (50%). The wood soaks up the epoxy mix like a sponge and the whole thing becomes just as strong as the original cover material. It is also hot fuel proof!! The 1/16" balsa top forms easily to the curvature of the frame rails, which are made of 3/16" basswood. Use Zap® or any other cyanoacrylate adhesive (super glue) to facilitate assembly. Once you get the basic frame glued up, use some 5 minute epoxy to add the corner gussets (right photo). Add the top by starting at the rear/bottom edge (flat area). As you approach the curved portion of the rails, tack the top down a bit at a time, using the super glue as you form/roll the balsa down along the curve. Apply a few more drops of glue, roll the top a bit more, hold it for a few seconds, and repeat until you have worked your way to the front/top edge. Once the top has been added, strengthen all the joints with epoxy. Trim any overhang, sand to shape then apply 2 coats of the epoxy/acetone mix, with a light sanding between coats. After the last coat has completely cured, spray on some primer/filler, lightly sand again then finish with flat or semi-flat paint. Once the paint has dried, epoxy it in place over the gaping hole in the cover. I also used some RTV to caulk the edges just to make sure the interface was water-tight.