Since this is an O-Scale layout I wanted the surface to be solid so I installed MDF board on each module. I hinged them so I could easily work on the wiring rather than crawl underneath. I used standard door hinges from the local big-box hardware store. I have found that once I finished the wiring and tested everything I would rarely need to mess with it again. My prior N-Scale layout used thin plywood for the surface. I also had remote switches controlled from a control panel. This current layout only has manual Gargraves switches. This means the only holes in the surface are feeder wires to the track.