I'm a bit late coming onto this thread, but when I wanted to recover ny 10' semi scale rudder/elevator Minimoa I went along to our local glider airfield and found the bloke who does most of the repairs on the fabric covered full size jobs. I asked him what the lightest material they used and he showed me some lovely heat shrink nylon stuff. I asked him if he had any off cuts that I could possibly use and what it was for. He gave me what he called off cuts and there was enough to cover the Minimoa, Grunau Baby and a lot over. so, what I am coming to is that if you are near a full size site it could well be worth a look?
Carefully cut to size and stuck down with balsa lock glue and ironed it is about as close to bullet proof as you can get. Clear dope covering and it looks the total dogs what-nots!
