Abstract: A human part model is formed by spraying a layer of uncured silicone mixed with a catalyst and a solvent carrier onto the inside of a mould cavity. Next a model base is clamped to the mould and a body of uncured silicone gel mixed with a catalyst injected to fill the mould between the base and the layer. As the silicone layer cures, it adheres to the body of silicone gel, thereby enhancing the life-likeness of the resulting model. A breast cyst model may be formed by adding an elastomeric bulb to the base prior to clamping the base to the mould. The inlet of the bulb is inserted onto a passageway through the base, which passageway has a one-way valve to prevent backflow from the bulb. The hardness and thickness of the bulb is chosen so that it reseals after being needled.