Why build your own wooden bike fenders when you can buy perfectly good fenders at the store? Because they're cool, and they show that you care.
I was able to adapt some lessons learned from my experience building my rowboat. For that project, I learned how to steam-bend wood (white oak for the ribs of the boat).
I used two different bending methods for the front and the rear fender, mostly just to see how well they would each work. The front is laminated from two thin layers, while the back is soaked, heated, and bent. Both worked. Details follow.
Front fender (laminated)
I cut two thin strips of oak (pieces of oak flooring inherited from my grandpa, a carpenter who never threw away a good piece of wood). I cut them about 1mm thick on my 1953 DeWalt radial arm saw.
Cutting the wood that thin was difficult. It was easy to have the piece bind or break.
I then took two pieces, and secured them to the rim of a 27" wheel (they were to go over a 700c x 32mm tire, and I thought the 27" rim would be a good size, allowing for some "bounce-back" of the curvature. I was right.) I secured them in at the end with a cable tie. I then spread glue on the lower one to get ready for clamping. For a clamp, I used a nylon webbing tie-down strap, the kind with a metal ratcheting handle. I put this around the outside of the wheel/fender combo, and tightened it up. Note to self: next time, align the edges of the 2 pieces better before clamping down hard!
I used Titebond III, and liked the results. Prepare for a lot of glue squeeze-out!
TODO: describe cutting and finishing.
TODO: describe rear fender (steam-bent) method