If, as I think you are, you are asking for some examples he could use as design samples from their pictures, there are a lot including Dirty Bird, Georgetown Pottery, SRD, many on Etsy.com, etc, etc. Most are one piece, doubled bowled.

Personally, I have found that after a while they all take up space and become superfluous. A cup sitting in a sink of hot water or two small bowls nestled together work fine. Over the last two years, I have transitioned almost exclusively to face lathering, often with cold, cool or lukewarm water after being obsessed with hot lather at first.