Plaster is a very versatile material used to create models. When plaster is poured into a mold, it fills the spaces of the mold and produces a model replica. If you want to see what your teeth look like up close, make a plaster model of them. Working with plaster is as easy as mixing the powder with water and pouring it into a mold to dry. Things You'll NeedBoil-and-bite mouth guardMold release sprayFill a pot with water and set it on the stove until the water boils. Dip the mouth guard into the water for one minute so the plastic becomes very soft. Remove the mouth guard from the pot and run it under cold water for a few seconds so the surface doesn't burn you. Insert the mouth guard into your mouth and bite down hard to leave the imprint of your teeth in the plastic. Remove it from your mouth and run it under cold water to set the imprint of your teeth. Spray the indented mouth guard with mold-release spray so the plaster will not stick inside the mold when it dries. Mix up your plaster according to the manufacturer's instructions and scoop it into the mouth guard mold. Use a Popsicle stick to level the top of the plaster in the mold. Leave the plaster to dry in the mouth guard mold until it is hard to the touch. This will take about one hour. When the plaster has dried, turn the mold upside down and pop out your finished teeth model.