A number of manufacturers and individual artisans offer moulds specifically for making polymer clay dolls. However, you can also use moulds intended for porcelain dolls. These moulds are usually two-piece moulds made of plaster that fit together using a series of interlocking bumps. The main difficulty with such moulds comes from removing the cast part without distorting the polymer clay in the process. This ultimately comes down to skill, but there are a few tricks that you can use to aid in the process.
Select a polymer clay that has the same flesh tone you wish to achieve in your doll. Tear off a piece large enough to fit in your mould and roll it into a ball in your hands. Make sure that there are no creases in the ball. If there are, smooth the clay over them using your fingers.
Spray the inside of the mould with a light misting of water from a spray bottle. This will prevent the clay from sticking to the mould.
Place the clay ball in one half of the mould. If the mould's cavity is somewhat oblong in shape, you can roll the ball into more of an oval so that it fits better. Press the clay into the mould with your fingers. Apply more pressure to areas with greater recesses, such as the nose and possibly the fingers.
Add more clay on top of the clay that you pressed into the mould if it appears too flat to fill the second half of the mould. Smooth away any creases and cracks in the clay with your fingers. Place the top of the mould over the clay and press down so that the two halves of the mould lock together.
Place the mould in the refrigerator for half an hour. Cooling the clay will make it less susceptible to bending and scratching when you remove it.
Remove the mould from the refrigerator and carefully lift the top of the mould off of the clay. Trim away any excess clay around the cast figurine inside using a craft knife. Remove the clay figurine carefully and pose it.
Place the figurine on a metal baking tray. Prop up the arms and other extremities using aluminium foil. This will keep them from sagging as the piece cooks.
Set the oven to 135 degrees Celsius and bake the figurine for fifteen minutes.