Use a sheet of plywood at least 8 inches wider and longer than your planned volcano to make the base, to prevent the lava from staining surfaces during eruptions.
Use salt dough, plaster or papier-mâché to form a mountain around an empty 2-liter bottle placed upright at the center of the plywood base. Be sure to leave the lid off.
Form the model volcano's open top tightly around the mouth of the bottle.
Make ridges and channels beginning at the volcano's top and ending at the base of the volcano for the lava to flow through.
Let the volcano dry completely, then paint it with acrylics or spray paint. Plastic aquarium plants can be clipped and glued to the volcano for trees.
Spray the volcano and plywood with a clear sealant after the paint has dried.
Mix 1 tbsp. liquid dish washing soap, 1 tbsp. baking soda and a few drops of red food coloring in a cup.
Pour the mixture carefully into the bottle.
Set the volcano in an open area, preferably outside.
Pour 1/4 c. white vinegar into the bottle and stand back to watch your volcano erupt!