You're going to make a mess. Know this and prepare in advance. Lay down a drop cloth if you have one, or ensure that all nearby porous surfaces are covered with plastic or newspaper. Gather all your materials together as it will be difficult to get, say, another bucket when your hands are covered in alginate.
You will need:
- alginate, the stuff dentists use to cast your teeth. There are a couple different brands, we used Dermagel brand from Douglas & Sturgess.
- three measuring cups of at least one quart capacity: one for the alginate, one for the plaster powder, and one for the water (don't get any of these materials mixed together at all until you are ready to use them)
- a bucket to mix the alginate in
- some plaster-impregnated cheesecloth, again from Douglas & Sturgess
- a couple of bowls for water, one for each helper
- two measuring cup
- a big bucket to mix the plaster in
- something to mix the powdered plaster with; a power drill mixer attachment is ideal but a metal whisk will do
- paper towels
- something to rest the mold in while you pour; a cardboard box with a towel or some packing material in it works well
- a brave volunteer! wearing an old t-shirt that can get tossed out afterwards (the castee will get very gloopy but the casters won't usually ruin their clothing)
Before getting started, cut some of the plaster-impregnated cheesecloth into strips, about an inch or two wide and three or four inches long. You need about 2-3 times as many as are in the picture. Also cut some much smaller pieces, an inch or two by a quarter inch, to use in the nostril area.