Before I started assembling the support structure, I cut 10-degree bevels on the bottom ends of the long support beams. I did this only for aesthetics.
I made a 10-degree insert for my sled to cut the bevels.
I drilled a million dowel holes in the ends of the cross braces and sides of the beams. Then I glued the structure sideways, one “story” at a time.
I worked quickly, then rotated the structure so it was upside down on my bench to keep it flat. I clamped across the cross braces and added the horizontal leg support plates on each end. I was not sure how well the support plates would hold up, so attached them with screws in case I ever needed to replace them.