Explain to your model that you are about to cast a mold after his body in two parts -- the front and the back.
Divide the body into the front and the back using a marker or an eye liner.
Place the model on a table or a bed. Cover the front of the body with plastic wrap. This protects the skin and prevents the plaster from sticking to it.
Cut strips of plaster bandage, which is gauze with plaster in it. Dip the bandage into water and apply it to the model's body. Apply horizontal layers first and then vertical layers, making sure to cover the entire surface of the front part and create a cast that is at least 2 inches thick. As an alternative, prepare plaster with equal amounts of plaster and water. Cut strips of gauze and apply the plaster on them using a paintbrush.
Allow the plaster to harden for 20 minutes and remove the cast from the model.
Prepare a cast after the model's back as well.
Allow the plaster to cure overnight.
Varnish the inside of the molds. The varnish acts as a release agent and keeps the plaster sculpture from sticking to the mold.
Join the two halves of the mold using rubber bands. Apply wet plaster bandages around the joints and allow to dry. Drill a hole on the top of the mold. You will use this hole when casting the sculpture.
Prepare plaster in a bucket using equal amounts of powdered plaster and water.
Place the mold against a wall or have someone hold the mold while you pour the plaster into it using the hole you drilled. Fill the entire sculpture with plaster.
Allow the plaster sculpture to harden and remove the mold from around it. Use a pair of scissors to cut around the joints of the mold.
Sand the plaster sculpture and carve details such as the hair or the eyes using a chisel, a knitting needle or the tip of a knife.