I have plunged head way into a possible folly of a layout design. I decided that since I move so often I needed a portable layout; also since I plan to one day be stable in location and have a large room; I wanted an expandable layout; hence modular.
I have built a 16 x 9 foot oval out of 20 inch by 36 inch sections. Each is composed of MDF rails cut to 1 x 3 dimensions with a surface of fiberboard. (Light and cheap) The secitons are bolted together and each is suported by two legs (2x2) which are bolted to the MDF. I am using cork roadbed on top of the fiber board to buildup thickness for attaching track and have gargraves flex track on two mainlines with 72" curves and 8 1/4 track centers. Each section will be its own block and be wired to control the adjacent two blocks using the outside rail technique. (No DCC; mostly post war stock and definitely a post-war mindset!)
If this were a permanent layout I would have prefered to go with 1/2 plywood with homosote and 1 x 4’s but wanted to keep the sections light enough that I could easily carry one in each hand.