[Kevin Sevcik]

All square aluminum tube is extruded. Or most all. It's just not fancy extrusion. That said, 1/16" wall 1"x1" square tube isn't my first choice for structural material. For anything seeing over a moderate load, it's probably actually my last choice. Certainly, I don't think you'd need 60' of it unless you're going to prototype your entire robot out of it and then make another one out of 1/8" wall aluminum. It is possible to weld it, but you need to make sure you get an alloy with good weldability. 6061 and 6063 are god choices and you'll likely find square tube in those alloys. However, you might also find it in 2024 or other alloys which are much harder to work with. Also remember that any aluminum welding you do is quite likely to ruin your temper for a fair distance around the weld.