I was gonna say 80/20 too. They are more reasonably priced then some. You can get different types of extrusion from them. They have several series each having different sizes, with different weight and strenth characteristics for different needs.
There use to be a guy on ebay that sold 80/20 surpluss. He had a decent selection of the stuff, and is probably priced much better.
What your looking for may be different then this, and they do sell wider pieces then this, but here is a pic of a piece that I have a few lenths of, and use ocasionally. It's 2 slot with slots on both top and bottom, and the sides have 1 slot on them. It's black anodized but you can get the alloy color too. It's heavy, and nice & ridgid IMO. I think It comes from either the series 25 or 30, but not sure because It's been a while since I bought the stuff. Some of the stuff is lite duty, so be aware of that when purchasing.
Bosch is another that makes the stuff, but is more expensive. There are other too.
PM sent with info
Greg
