The backdrop framework is covered with 1/8 " masonite panels. These are glued to the framework with panel adhesive so there are no nail or screw holes in the panels.
The panels leave a gap above the TGI beam. The joists for the benchwork will attach to the TGI beams here. The track and scenery will all be above the gap. The scenery will dip below this level at Sulphur Gulch but that is a story for later.
All seams between panels were filled and sanded to provide a seamless surface. The entire set of panels was then lightly sanded to insure that the wallpaper paste would adhere to the surface.