Rub plenty of patroleum jelly over the area of skin you want to cast, to prevent hair from catching in the plaster.
Cut 12 to 18-inch strips from a roll of plaster. Use sharp scissors to avoid creating frayed edges.
Pose for the casting, but keep in mind that creating the cast could take a long time. Try a standing position, or lie down on your stomach. This pose works well if you are making a cast of your backside. Similarly, lie on your back if you are making a cast of the front of your body. Alternatively, you may want to sit up with your hands resting on your stomach if you are pregnant.
Dip each plaster strip into a bowl of tepid water and apply to the desired area of your body. If you are planning to include your arms and hands in the cast, you will need someone to apply the plaster for you. Place small squares of plaster over nipples and the belly button and mould these into shape. Apply three layers to the cast area, but avoid placing more than one layer over the nipples and belly button. Add another layer of plaster strips around the edge of the cast to strengthen it.
Sit still and wait 25 minutes before removing the cast. Leave the completed cast to air dry for 48 hours to allow it to set.