I don't have the same understanding of "crutch" as Campy has. If you take a round (approximately) fuselage with stringers down the horizontal center line of the formers. Cut the formers horizontally in half. Pin the horizontal stringers to the plan, then glue the former halves to the stringers. Complete this half of the fuselage. Remove this half of the fuselage from the board, turn it over, glue the other halves of the formers in place, and complete the fuselage construction. The original stringers that were pinned to the plan, are the "crutch". I will be building an OLD, redesigned (by me) Mosquito that uses this method and will try to post pictures, but it will be some time away. Advantages are that you can hold the "crutch" flat while you build, without having to worry about jigging up round fuselage formers.

Les