Easy to do? Seems like this; jigs simply consisted in a 1:1 copy of the construction drawing on a wood surface with the blocks to give the shape to the rib.

These are the original Falco jigs, the ones that were used to build the production Falcos. The strange thing is that these jigs proved to be not so accurate. Is this the reason the production Falcos have a better roll rate than the homebuilt ones? We'll see....