The right answer is wax.
The waxes are of synthetic, natural, animal or plant origin composed of long and branched chains which gives them a microcrystalline structure. This results in a soft, white, non-translucent substance whose melting temperature is arround 70 ° C.
The melt temperature of the clay exceeds 1000 ° C.
It is clear that wood and metal are not used for low temperature molding.