I need to flatten some lengths of copper tube for a project, and haven't figured out the best way to do it. I want to start with some 3/8 or 1/2" copper tube (in 3 or 4 foot lengths), flatten it to into an oval/ellipse that's about half the original diameter, and then braze or solder it to the rest of the radiator/heat exchanger. Anybody done this before? I need to make a few of these, so I thought about having some dies made for a Pexto-type bead roller--maybe make two sets, one to go halfway, then another to finish it? I'd like to do this with a hand-crank machine, but maybe I'll need hydraulics? If anybody has pics or links of something they've made or bought, I'd love to see it.