Sailrite (http://www.sailrite.com) has a book on building spinnakers.

Sailcut (http://www.sailcut.com) has free CAD software, which
might work for your panel layouts if you don't mind hand
lofting the panels or investing in some plotting capability.

There are more tips in the book "The Sailmaker's Apprentice"
but I think the Sailrite book has enough info for someone
familiar with sewing.

I have been asked to make an light air asymetrical cruising spinnaker
for a Haida 26 sailboat.
Anyone have access to patterns or can recommend a sailmaker's bible
that would give me enough info to design and make this sail?