Well I attempted to bend up my exhaust header pipe. NUTS!!!!! Made a bending jig. Capped 1 end of pipe and filled with water, then capped the other end. Man I tell you it took some muscle to bend the pipe, wow. But then it bent, AND KINKED.[X(][:@][&o] Next I will fill the pipe with sand past the bending area. Put a dowel in the rest of the pipe. I will also make a better bending fulcrum, deeper (more matching) concave groove to match the pipe radius. And while digging in my parts bins I found another muffler adapter, so I can just bolt them together to exit the engine cowl. Still have to have the header pipe and bend back to aircraft center line. Right now it is exactly lined up with the right landing gear strut. Muffler and gear strut can't occupy the same real estate.
I doped the entire aircraft (all surfaces including control surfaces) with nitrate dope. I did that outside, that be some stinky stuff! The light sanded with 400 grit. The dope penetrated the light spackling I was so concerned about, and it appears to be much harder and more crack and chip resistant. I still may remove the spackling were I put it around control cable sheaths. As an experiment I mixed some light spackling, Epoxy, and micro balloons together. Very robust, hard but flexible. Still somewhat sand-able. I will just shape and smooth with a wet finger.
Getting close to fabric.