Another vote for buying one
Unless you are a skilled woodworker with steam woodbending equipment, I highly recommend you buy one of the curved models available at West Marine or BoatUS. They will not only look much nicer than anything you can make at home, they work better ergonomically. I had a homemade oak (I think) tiller on my Oday 23. It was a straight stick, rounded on the sides and at the end. I was always complaining about how I had to reach down to steer, and how it would hit the knees or stomach of the person sitting across from me in the cockpit when we tacked. For our anniversary, my wife bought me a tiller made by H&L. It is a stock model that is a direct replacement for a Coronado 25/Oday 27. It is the same length as the homemade job, but it is a beautiful piece of woodworking with alternating layers of ash and mahogany. It has a big upswept curve in it, putting the steering grip in a very comfortable position. I am also no longer banging into my seatmates.