[Cory]

your point that you must buy 80/20's actual material is true, and making them yourself is no doubt cheaper, however, these cubes are made of aluminum, they are not friction-fit, and they are reusable. We used the cubes when constructing our cart frame last year. The cubes themselves arent tapped, but you tap the hole in the end of the 80/20 then you can bolt pieces together nice and square.