Okay! Time to put some thought into manufacturing....
In cost order $-->$$$
Resin Options
Epoxy
Polyester
???
Template Options
Cardboard+
Skin on rib (like cardpaper on ribs (wood?)
Foam - medium density insulation stuff (pink or blue)+
Core Options
Cardboard+
Foam -insulation type+
CoreMat (cheap bulking stuff)
Purposed Foam Cores
Fiber
Plain Weave Glass
Biaxial Weave Glass
Polyester resin is cheaper, but nastier to work with. The stuff at the hardware store is pretty nasty to work with (all gloopy and difficult to work out). Epoxy is more expensive, but "safer"
Templates.... If I use cardboard, I can use that as the core. The downside to cardboard is it's difficult to shape exactly as I want. I can also use insulation foam as both the template and core. It's more expensive (ie, not free) but I can shape it much easier. If I use foam, I must use epoxy because I'm not willing to spend even more money on urethane foam that's compatible with polyester.
Cores.... If cardboard or insulation foam are used for templates, they'd probably be used as the core. For even more strength, however, I could use purposed foam core. CoreMat is cheap and decently strong, but will be heavy.
Fibers.... Plain weave is anisotropic - it's strong in one direction, but not the other. That means, I'd need to have more than one layer in different directions. Biaxial is strong in two directions, but a little more money per linear yd. The biaxial stuff is heavier - but significantly stronger. Per pound, biaxial is cheaper
I'll post dollar figures later... Now it's off to the bookstore...