PaulIE has a great Instructable for bending tubing. He writes “Here I show how to bend aluminum tubing. This is basically documentation of how I built a new bow rail for my sailboat. I trace the curve that I want on some scrap lumber. This scrap will be used to build the bending jig. I’m just using a couple of old 2×4’s. You wood should be somewhat thicker than the diameter of the tub you wish to bend.” Link.