ChazInMt,
You are facing the same issues in covering your 'cap that traditional boat
builders do when planking a hull; How can you quickly, accurately, and
repeatably find the true correct shape of planks that bend and twist to
conform to the ribs?
The process is called "spileing" and it is a purely mechanical way to generate
the needed shapes accurately -- no special tools, no computer needed.
Here is a place to start:
Spileing .