I know where you can get big blocks of styrofoam. If you go to your Tractor Supply store or Orchelens or anywhere that carries small pull behind trailers. When these arrive at the stores they come packaged with the large solid stryrofoam blocks inbetween each trailor, to keep them from rubbing togehter and scratching the paint. We got about 50 of them one time from a store. They just throw them away. We used ours in Artic Edge for blocks of ice, then in Game Day as benches, and now shaped for rocks. GOOD LUCK