I have a tube that turns out to be too short for my purposes. It is already primed white on the exterior, and has had the plastic coating removed from the inside. It is 1/4" thick and weighs about 20 pounds. It was manufactured as a concrete form by a company called Brock White.
I paid about $45 for it, but it is no use to me. But it should be of use to someone! It's yours for free if you come fetch it. I live in Maple Plain, Minnesota, and have no desire to ship this large item.