I bought some foam insulation board to put a temporary layout on because I thought I was going to move to a new house. well as it turns out I plan to stay in this house. I was impressed with the way the foam has lasted for a year. So far it has not warped and adds to quietness to the layout. Now this layout is about 14x24 ft.long. To save money I did not put plywood under the foam for support,instead I cut the foam into 2x8 ft. strips and supported it by 12 inch wall brackets every foot and a half around this shelf layout. I then used 2x2 inch lumber cut at the right height for legs every 2 feet or so. I applied scenery and track. The track was glued using a low heat glue gun. I used small L brackets to keep the legs from wobbling and then put long drywall screws to join the insulation board to the legs. Trees,telephone poles can be poked into the foam. My heaviest engines 2-10-2s,ac6000s run fine on the layout. I did add onto this layout and I used plywood for the base on the new section. I have back trouble once and a while and this foam insulation board was just the ticket. This kind of a layout would be great for z scale n scale or ho scale,just an idea that works for me. MAY GOD BLESS.