re: TV Tray

Yes, the horizontal piece at the top of the inside leg assembly is a 3/4” dowel, which seems to be fairly common. What varies with different designs is how that piece is captured when it travels from front to back as the legs are opened and closed. I chose to make 2 long C shaped pieces that keep the dowel contained as the legs are opened and closed and act as a stop on each end. You can see those pieces in the main photo. I had to make these pieces twice to get them right. 

The order of assembly was important; outside braces glued and screwed to the top first, outside legs attached to the braces next with binding posts, inside leg assembly attached to outer legs, C shaped pieces doweled and glued last. I spent much more time thinking things through than it took to actually assemble it.