I have built three stands from 8020. I purchased through 8020.net, usually takes around a month to ship.
I did not want any cut ends exposed if I could help it so my horizontal runs are between the vertical legs in shear. I used anchor fasteners which I believe are around 1000# in that configuration at each individual joint. I used external gussets (made from the same extrusion) for each top corner. Each corner has three gussets. I had a piece of 3/4” 6061 jetted for size and fasteners for the top. I counterbored each hole so the fastener wouldnt protrude. The bottoms I used 3/4 starboard, again had this jetted for the extrusion cutouts. The bottom doesn’t need holes for fasteners as it’s held captive by the legs. I had my cutouts made around .007” undersize, this eliminates any annoying gap. Make sure to have the leg ends tapped to thread matching you feet, using feet makes leveling a breeze. If you tap yourself spiral flute taps work the best since the extrusion profile I used had notches in the center hole.
I used 1515s for both 40x32 and 48x32 stands. The 40x32 has four legs and the 48x32 six. I checked deflection in the middle of the long run on the 40x32 with a dial indicator as I filled. It had no deflection and zero racking. I think we tend to way overbuild, I probably would have been fine with 1010s.
