Plaster Molds are used in pottery because they absorb water out of the clay as it dries.  This keeps clay from sticking to them, and helps reduce warping.  The molds sold here are for texturing or forming clay.

We also sell glass molds and more glass molds which are made of ceramic (not plaster) so they can be fired in a kiln.  These glass molds can also be used for forming clay and work similarly (clay does not stick to them.)  And we have slump-hump molds which are plastic and can be used as is or to create your own plaster molds.

If you are looking for slip-casting molds, where you pour slip into a mold to form an object, we do not carry those.  We do however sell the casting slip.