In the days before computers a lot of stitch and glue panel shapes were developed by trial and error. I supose you could calculate and draw out the panel shapes by hand, but the very idea gives me a headache.

But there is an easier way. You use standard lofting techniques (which I can't explain here, but there are several good books on the subject). Working from plans or offsets you make station forms and mount them on a strongback. Then you use traditional planking techniques where each plywood panel corresponds to a plank. Several of John Gardner's books have good descriptions on how to "spile" and "get out" planking.

I'm about halfway there for the next kayak I'm going to build. The boat is lofted at full size and the station shapes are stored in the computer. The next step is to build a strongback and cut the stations out.