I'd build a kite first which would allow you to make mistakes without costing you too much canopy material. Once you've got something that looks about right then do the real deal.
I don't know you'd be able to jump your canopy without dispensation (and you'd have to use a cutaway rig in any case).
But yeah.. gotta admire your aspiration to do this. I am sure you will learn a lot on how they are made, how the deployment sequence works, how they fly and a ton of other stuff in the process even if you don't eventually produce the jumpable product.
Good luck
P.S. realised I'd kinda paraphrased the guy above. ^^^ What he said.
(This post was edited by adamUK on Jul 11, 2012, 1:31 PM)
Edit Log:
Post edited by adamUK
() on Jul 11, 2012, 1:31 PM: Postscript added.