Hi MADD
They sell this hard foam insulator stuff at Home Depot..... 4 feet by 8 feet sheets.. very very good stuff to build walls with. They are very light and strong. It is easy to build a track for them and they slide nicely.

If you would ike to see a 10 x 12 X 8 room split into three sections using this stuff check out http://www.seemorebuds.com

good luck