Do you have a polystyrene board and a few CD cases? Get your own fake whiteboard or a cutting mat then! Mark the outline, follow it with a cutter, use some tape on the ends, cut white papers for the cd cases if you want to and glue it all together.
INSULATION A cross-section diagram of a suspended slab floor. Underneath the slab is a layer of polystyrene board, which is attached by a retaining pin with an expanding plug end. Sections are sealed to one another using tape.