Chavant NSP hard modelling clay
Chavant Clay is a professional, *sulphur free sculpting clay that can be melted to pour into a mould, for instance, to create as base from which to features can be added.
The clay hardens quickly after pouring and can be sculpted at room temperature. If you need to smooth an area, you can gently warm it and moisten with water.
*Sulphur can often caused inhibition problems with various liquid silicone rubber mould-making materials.