To get this double pattern effect I rolled a bolt across the whole slab before painting any colored slips on the slab of porcelain paper clay (which is indeed totally functional).
I brush on three layers of colored slips and then when they are dry enough I scrap designs through all the layers. The clay is then rolled out to produce a more painterly slab as the thick and thin layers of colored slip are spread out.
The pieces are all dishwasher and microwave safe.