a compound like this has been mentioned a couple of times here . if you read all through the ebay listing you’ll see they tell you how to make it , so you don’t even need to buy it [:)]
I got a 25lb bag of PERLITED Gypsum Plasters (eg Structo-Lite ™ and Gypsolite ™) from the local Home depot. It is a lot cheaper than buying these purpose made mixtures.
Save your money – this is something you can mix yourself. The recipe is
1 cup Celluclay (papier mache)
1 cup Vermiculite (from a garden shop)
2/3 cup white glue
1 capful of Lysol
1/2 to 1 cup Tobacco Brown paint
Water
Mix to a spreadable consistency. Store unused Goop in an airtight container.
Celluclay is very expensive for what you get – $5 per pound at Michael’s in Tucson, Arizona.
I have come up with my own, cheaper version using some items I had left over:
Drywall joint compound (dry, powdered version)
Thin-Set ceramic tile mortar (how much depends on the desired sandy look)
Sawdust
Real, honest to goodness Arizona dirt from my back yard
White glue
Cinnamon Brown or other color Apple brand paint from Wal-mart
Water
Sometimes, I substitute Hamster bedding from Wal-mart, which is shredded Aspen wood, or Real Comfort Hamster, Rabbitt, and Gerbil bedding, which is shredded paper, in place of the sawdust or Celluclay; and sometimes I used the strips of paper from my document shredder.
I build up a rough shape of my mountains using styrofoam and them slop this mixture over the top and sides to cover it. Trees, bushes, etc. can be “planted” while the mixture is still wet and you don’t need to go back later and apply them with white glue.