Q: Does anyone know how to make stamps for ceramic?
A: If you are talking about a rubber stamp, the process involves making a photo-etched metal plate from the line-art original, then vulcanizing rubber into the plate, peeling it off, and mounting it to a piece of wood.
If you don’t have access to a vulcanizing press, (although custom rubber stamp service isn’t too hard to find most places) you can use RTV (room temperature vulcanizing) rubber. This usually consists of two liquid parts which are mixed together. It will set without heat or pressure. This is good for more dimensional contoured impressions; the etched stamps give a fixed depth.
However, plaster works better than rubber for pressing into clay. The easiest way to make a plaster stamp is to cast a small piece of plaster, and when it has set to scratch a design (in reverse) into its flat surface. The impression will show a raised line where the incised line was. For more dimensional stamps, roll out a piece of clay, impress a design into it, then cast plaster over that. This will yield a stamp that will replicate the look of the original clay impression.