This is a simple overview of how to make ceramic plates using a plaster mold. Using molds ensures that your pieces are all identical, if that's the look you're going for!
Step 1: Roll a Slab
Using either a slab roller or a simple rolling pin, roll out a slab of clay to about 1/8"-1/4" thick. If you're using a rolling pin, roll it out as if you're making a pie crust. Make sure the slab is big enough to hang over the edges of the mold. Use a rubber rib to smooth out any texture left from the canvas or rolling pin.
Step 2: Drape Slab Over Mold
Carefully drape the slab of clay over the mold. Press the clay lightly, so it conforms to the full surface of the mold.
Step 3: Cut Off Excess Clay
Using a knife or wire cutter, slice off the excess clay around the edges of the mold. Try to maintain the same angle with your cutter the whole way around the plate.
Step 4: Smooth Edges and Leave to Dry
Using your fingers, smooth the edges of the plate. If necessary, use water to moisten the edges if it's cracking. Leave the plate on the mold to dry completely while wrapped in plastic sheet. Once it is dry (this could take up to two weeks), bisque fire, glaze, and glaze fire the plate as you would with any other ceramic piece.