I made a fake rock foundation using drink carrier trays for the back and sides.

That turned out really great.  I have saved some of that material and a bunch of egg cartons but have yet tried to use it.  

Very nice.......

Keifer, that was probably one of the easiest things to do.  I cut 1 1/2 inch strips of cereal box, covered them with strips of raised design paper towels dipped into ModPodge, then tore pieces of the rough part of the drink carrier, dipped them into modpodge and layed them as close together as I could.  (they shrink).  Painted a bit of color onto them.  They look so much like stone. It is amazing.  Found the instructions on the web.  Can't remember who posted it though.

That foundation looks wonderful!! It adds some nice texture to the house, too.