[Molten]

Aluminum tubing works well. However it does have a major obstacle to overcome. As with all aluminum, you must overcome the fact that it likes to gum up when being rubbed up against itself. You would have to design some sort of system to make them roll properly. Perhaps someone else has a better suggestion, but this is just something that I would look into until they do. It might really work well for you. Also, lubrication will not make up for the gumming up of the aluminum.