Foam sheet with 3/16” +\- top and bottom skins glued with polyurethane adhesive. I’d go with 2” foam. It’ll be strong enough and stiff enough, but maybe a concentrated load like a small chair leg would damage the skin. Make a section and see. It’s o.k. to **** pieces of foam together to get your 3’ x 5’ sections (foam comes 4’ x 8’ ). It’s the skins that handle the tension and compression forces, not the foam core. Not sure what your price would be.
