Things You'll Need
Instructions
Fill a round balloon with air until it has a 12-inch diameter.
Mix plaster of Paris with water in a shallow plastic dishpan, according to package directions.
Dip coarse-weave burlap into the plaster mix. Mold the plaster-soaked burlap over the balloon in wrinkles and folds. Allow to dry for 10 minutes.
Once plaster has begun to set but has not completely hardened, poke a sharpened awl through the burlap in multiple places to break the balloon and to create small holes all over the outer surface of your cave model.
Carefully enlarge some of the holes on top of the cave model to 1/8-inch diameter or larger, but less than 1/2-inch diameter.
Mix a second batch of plaster of Paris. Pour the plaster mix over your cave model so that it runs through the holes on top and into the cave. Allow to dry overnight.
Use scissors or a utility knife to cut a viewing hole in the side of your cave model. The flowing plaster should have become simulated stalactites and stalagmites.
Place your cave model on an 18-inch square of unfinished 1/4-inch thick plywood or Masonite. Use Spanish moss, sisal fiber, twigs, coffee grounds, sand and sawdust to create a textured landscape for the approach to your model cave's entrance.