Wow if I had some time on my hands, I would make these. The author used an old bike wheel to bend the wood, that was soaked in water for 3 days. It looks pretty cool on the bike once finished. I think I would reuse a few other parts from old fender (like the spoke bar things) just in case to keep it in shape.
http://www.instructables.com/id/bicycle-wood-fender/?ALLSTEPS