Started filling rivets on the fuselage bottom using a polyester resin thickened slightly with talc. This is the method Simon & PGC have used which appears to work well. The formula I'm using is 5ml resin, 1 level teaspoon talc & 3 drops catalyst hardener, this gives me enough time @ 20 degrees room temperature to use all of the mix before it "goes off". Application is with the sharp point of a bamboo skewer ensuring the resin travels to the bottom of the rivet hole. I'm about 2/3 the way along the skins after only 2 batches mixed. PGC recommends filling all rivets prior to sanding, I'll do that.