Tear or cut the plaster fabric strips (which can be purchased at any craft or medical supply store) into 4-inch strips.
Mix the plaster of paris, Elmer's glue and one cup of water together in a bowl.
Push any hair out of the face of the person you are casting, and cover her face with petroleum jelly. Cover the eyebrows, eyelashes and any other facial hair with tissue to provide extra protection from the cast. The tissue will stick to the face due to the petroleum jelly.
Place the plaster strips onto the face. Smooth the strips, overlap the edges and apply them along a diagonal. Cover the entire face with two to three layers of the strips, leaving an opening for the nostrils.
Allow the cast to dry for 10 to 20 minutes. Instruct the person with the applied cast to hold very still. The plaster strips may get slightly warm during the drying process.
Remove the cast, and pull off any remaining tissue. Place plaster strips over the holes from the nostrils. This is the negative cast from which the positive plaster cast will be made.
Pour the Elmer's glue, plaster and water mixture into the cast, and allow the mixture to dry for several hours. Once dry, pull back the negative cast to reveal the positive cast of the face.