Two words “wood bending.”
Wood bending is a technique that was developed a long time ago. It is what they used to make boats and barrels. The process involves steaming the wood to make it more pliable, to achieve the shapes needed for each piece. The pieces take several days to make, but I enjoy the process. It amazes me every time I take a flat board and manipulate it into an angled piece of wood. If you are interested in learning more about wood bending there are several good reads on it that I can recommend, The Complete Manual of Wood Bending or the Woodworkers’s Guide to Bending Wood.