The base is 1/4" plywood, with quarter-round glued on the perimeter. The grass is a blend of a couple different turf powders, and was glued to thin painted styrofoam sheet before being sprayed with matte sealer. It is fairly robust to the touch. The porch floor is basswood strips (as is the parlor floor); the exterior paint is Olympic premium interior latex semi-gloss (my favorite) in "Mother-of-Pearl".
Thanks for looking!