Begin with a relatively thin slab of fresh clay; if it is really soft, allow it to dry a little to the point that the corner will stand up when bent (this entire process will be done with soft clay with no drying in between). Compress and smooth with a metal rib. Cut out desired shape for the wall piece, a square or rectangle works best, and start small for the first try (about 5″ x 5″ will do). These pieces look nice hung in multiples, so I often create a template out of scrap card stock (old exhibition post cards work nicely) that I can use over and over again. This will become the design inside the border of the piece. http://ceramicartsdaily.org/methods-techniques/quilting-with-clay-a-handbuilt-soft-slab-ceramic-wall-art-project/