Gary, I have 2 aluminium tubes made by Gary Mitchell in Sydney. He runs a metal fabrication workshop near the airport. He rolled a 12" tube for me that I used to hold a 10" mirror, and he's also rolled a 16" tube that I'm using to hold a 13.1" mirror.
You can see photos of the 13.1" tube here:
http://www.acquerra.com.au/astro/equipment/13/
They are fantastic tubes, the end rings make them very sturdy and they are light as well.
cheers, Bird