One of the lessons of building an airplane.... you often spend more time building stuff to allow you to build an airplane... Added a second 4' x 4' workbench to make an 8' x 4' workbench to start building elevator and rear wing. I also re-topped my original workbench... the MDF that I used last fall started sagging from moisture as well as the fact I didn't have stiffener stringers. Replaced that top with 1/2" plywood and added 16" on center stringers to workbench to stiffen and support new top. Repurposed MDF for lower shelf to store wood and tools. Amazingly, level all around within 1/8" on first go round.