Whatever you do, don't get the Ace hardware tubing. May be ok for light g loading, but it's usually "Plano" aluminum, whatever that is. T-6 tempered 7075 or 6061 tubing in thick wall should be available. I get it locally by the joint at commodity pricing-last time was Great Western Metals and before that was Farmers Copper. I think it's used for full scale or something like that.