I'd like, if I may, to add something here.
Maybe Jose used a poorly chosen phrase to express his idea.
Real is something that exists, thus, if you build, you are a real builder.
Artists like Da Vinci and so painted without jigs, it was free hand, and they did amazing things that way.
I totally agree that eyesight is the ultimate "jig", and that is why my mother calls me everytime she hangs a new Picture or painting on the wall, cause I can tell if it's not "straight".
I just don't think that I, Marcus, could build a straight wing free hand. Some people can.
Even the little Ringmaster I've been building for fun, I "jigged" the wing, but that's me.
Robert is right about the wood "twisting", and Bob Hunt in his lost foam vídeo talks about checking the wing for warps all the time, and I used a lot of eyeballing while building, but the jig was a lot of help.
I didn't mean to be disrespectful, only I think I can't build without a jig.
Marcus