RE: Sig Smith Miniplane build
Three #1 rules in soldering. Plenty of clean. Plenty of heat. Plenty of flux.
Latex and all other house paint will not stand up to glow fuel. It must be top coated with a clear ureathane or epoxy of some type. I have used minwax polyureathane spray with some sucsess.
In my experience, a perfect match to covering is all but impossible.