On the Aircoupe's I used lightweight body filler, I am debating on how to make the fillets on the Chipmunk. I may make some ribs and sheet over them with 1/16" balsa for the back half and just use some tri stock for the front half and sand to shape. The fillets are not that large on this plane so it may be difficult to form sheeting for the fillets. I also thought about trying some lightweight spackleing compound. It sands easily and I could then give it a light coating of epoxy after sanding. I will post how I make my fillets when I finally make up my mind.
I just finished drilling and tapping the wing mounting blocks and I am getting ready to put a 1/16 ply plate over the wing bolt holes for strength. I will then work on the wing saddle and get the 1/16" fillet base epoxied into position and start worrying about building the fillets.
Later!!
Anthony