I used a table with a "perfectly straight line" scribed on it, to position reverse image forms. The forms were cut from 1" building foam. I cut used two of the supplied forms as an outline. The reverse image forms worked as cradles. This is a slight modification of the method recommended in the excellent book "Kayaks You can Build" by Ted Moores and Greg Rossel. I highly recommend this book to anyone building a S&G kayak or canoe.

Have fun with your initial boat,
John Van Buren