Plaster of Paris, powdered gypsum plaster, is normally used with a mould. The mould is made of rubber or plastic and is made in the shape of a particular figure. Plaster mixed with water is then poured into the mould and left to dry. The mould is removed once the clay is dry and the result is a white figurine ready to paint or leave as it is. Forms can also be made from cardboard or a wire frame, fabric strips are then coated in the wet plaster are added over it in layers, and left until dry.
Prepare an area where you will do your sculpting work. It could be on a table top, desk or even on the floor. Place newspapers and plastic bags (if needed) underneath in case of spills.
Create an appropriate base or framework for your plaster of Paris sculpture. You can use wire to create a base for a figure or cut chicken wire into an appropriate shape with wire cutters to sculpt something like a mask. Once the framework for your basic figure is firmly held together, you'll be ready to begin putting on the plaster.
Mix the plaster of Paris as per instructions on the packaging. Normally you would use about 2 parts of plaster powder to 1 part water. Gradually add the powder to the water stirring well to dissolve any lumps and make a soupy, smooth consistency. It should be runny but thick too. Mix this in a bucket or large bowl.
Cut some strips of gauze or thin cotton fabric and dip each piece in the plaster mixture one at a time. Once the strip of fabric has been dipped long enough to be drenched in the liquid plaster, wrap it around the framework structure you created. Keep adding new strips in this way, allowing each one to dry before placing another piece on top. Cover the frame with enough layers to make it look even all over. Allow to dry completely once finished.
Sculpt your mask or figure once it is dry if you think it needs more defining. Carve lines around the eyes, nose and mouth. You can use sculpting tools from art supply shops or use any pointed object that will work. Paint your sculpture or leave it as it is.
Wear gloves so your hands don't dry out. Make sure your framework is strong enough to support the plaster.