Vaclav has a description of making carbon fiber tubing:
http://www.oneoceankayaks.com/Wshophtm/carb_tubing.htm

Qajaq USA has a link here to plans for carving a Greenland paddle:
www.qajaqusa.org/QK/makegreen2.pdf
I choose this route three years ago, and have grown to love the Greenland paddle. I like the $400 Werner carbon fiber paddles, but I can't bring myself to part with that much dough (or even half or a quarter that) when I can make a perfectly good Greenland stick from a $4 board. The debate ever rages between Greenland paddles and Euro blades. My vote goes to the GP.

Watch as Ross Leidy makes a Greenland paddle according to the plan above:
http://blueheronkayaks.com/kayak/index.html

On the NSW Sea Kayaking site down under, Norm Sanders shows how he made a lightweight GP:
http://www.nswseakayaker.asn.au/mag/30/paddle.html

CLC sells ferrules so you can make a take-apart paddle:
http://www.clcboats.com/paddles.php3?cart_id=CREATE
this was the first link I found to ferrules, sure if you dig a little you can find better choices. Look down towards the bottom of the CLC page.

Nick Schade has plans for a pretty nice looking Euro blade feathered paddle:
http://www.guillemot-kayaks.com/Building/Guillemot/Price/price.html#Paddle

I'm pretty sure you can do a great paddle with fiberglass, epoxy, carbon fiber, kevlar, maybe polyester resin, and maybe foam core with wooden stringers similar to surfboard construction.

I've been wondering about the possibilities of foam cored paddles myself, and not found too much info on it. Perhaps someone else knows more about this? Wasn't Shawn Baker fooling around with foam core paddles? I've stuck with wood (and my short GP, a "storm" paddle, has a light encapsulation of fiberglass cloth because the wood was pretty light and springy) because wood works fine for me, is strong, replaceable, good looking, and un-complicated. I think that if I wanted to make a decent CF paddle, the key would be in the layup and I just don't know enough about composites yet to make one efficiently and with a good strength/weight ratio.

Also seems like I saw a link around here not long ago where someone carved a mold from foam or something and was laying up carbon fiber Euro blades to attach to a shaft?