In article ,
Tim Wescott wrote:

Chances are the thing was designed for angle iron because the folks
doing the plans felt that'd be easiest to build, and because for a lot
of things 'easy' is better than 'absolute optimal weight/strength ratio'.

That was my guess. I'm just hoping to hear something like "2x2x1/8 will
do fine"

--
-Ed Falk,
http://thespamdiaries.blogspot.com/