A simple model volcano can be made at home with a few basic materials. The homemade volcano is a timeless science experiment, fun for children and adults of all ages. The project is intended to demonstrate a basic volcanic function by creating an "eruption" from a chemical reaction. The process of "building" the volcano, decorating it and, finally, watching it erupt is not only enjoyable but also safe and relatively simple.
Construct a stage for your volcano (this serves as the "ground"). If you plan on using the volcano indoors, consider making a stage with raised edges to prevent overflow. Let the volcano size dictate the stage size; make sure the edge is at least 6 inches away from the volcano base (all sides).
The stage needs to be sturdy enough to support your volcano without bending; a quarter-inch-thick sheet of plywood works fine for an outdoor volcano; a large baking tray works fine for an indoor volcano (triple-stacked, if using disposable pans).
Construct your "magma" chamber and vent. A 2-litre soft-drink bottle works fine for larger volcanoes; if you're building a smaller volcano, you can use a 591ml bottle. Almost any object with a small opening will work fine.
Glue the bottle in the centre of your stage (cap or top removed). Let the glue dry before proceeding.
Build your volcano's "body" or "cone." The most common method for building the cone is by using salt dough. You can make salt dough at home by combining two-parts salt, one-part flour and one-part water (for example, 2 cups of salt, 1 cup of flour and 1 cup of water). Use larger quantities for large volcanoes.
Form the salt dough around the bottle, forming a standard volcano cone shape. Consider gluing wadded newspaper to the bottle to help you form the shape. Let the salt dough air-dry for 24-hours.
Add detail to your volcano. While this step is optional, it will make your volcano more realistic. Paint the volcano (use acrylic paint or something similar).
You can add detail to your stage by brushing a layer of glue on the stage and covering it with sand or dirt. Adding a few small model trees (available at most craft stores) will also help.
Make your lava. Combine a few drops of red food colouring to one-part vinegar and one-part water. Pour this mixture into your "magma" chamber. If you want a bubbly eruption, consider adding a drop or two of liquid dish detergent.
When you're ready for your volcano to erupt, drop a tablespoon of baking soda into the chamber.
You can also use standard modelling clay or paper mache to form the cone. Modelling clay is very easy to work with, but paper mache and salt dough are more durable. You can use Diet Coke and Mentos candy to make a very explosive eruption. Add the Diet Coke immediately before the planned eruption (or it will go flat), and then add one or two pieces of Mentos candy. This method is recommended for outdoor use only.
Always wear safety goggles or other eye protection before starting the eruption. Stand a few feet away from the volcano.