I took two of my 5' original EAA Workbenches and cut them down to a lower height. I then built another EAA workbench that was 6' long at the same height. I bolted them together (top and bottom) so they are essentially one, 16' workbench now. I used 4x4 wooden post. I researched the uprights for many hours and looked at various designs from other builders and decided to go with wood 4x4 post as the instructions indicate. My logic is that I live in an area with pretty stable RH and I don't plan on these wings sitting in the jigs for years. We'll see how this "plan" works out in the future!