I have lined up the cardboard and roughly marked the profile with a pen. Over several iterations I have cut the cardboard down until it is a fairly close representation of the bulkhead profile.
Using the inner keel and gunn'al as reference points I have transferred the shape to my ply and cut the profile a quarter inch oversize. Using the same procedure as making the cardboard template I have slowly whittled the plywood to a close fit read to epoxy in place.
Holes for the inspection hatches were cut before final glue up. It is remarkable how much rigidity the bulkheads add to the whole structure.
I'm now ready to start painting the inside of the canoe.