I had problems when trying to make a windshield for a Nosen Citabria. The outline on the plans was way out or the model didn't matchup
with the plan outline. I remember reading in one of the model mags years before about fitting and making your own windshield pattern
out of paper and then transferring the outline to construction paper or poster board (same as Bob's cereal box pattern). I used poster
board and like Bob said it takes a few tries to get the fit you want.

Ron