Nerikomi is a classical form of pottery where different colored clays are rolled into cylinders, then cross-sectioned to reveal a pattern. So soothing to watch the string cut through!
Faith Rahill has a great step-by-step demonstration here:
Nerikomi (often referred to as "neriage") is a decorative process established in Japan that involves stacking colored clay and then slicing through the cross section to reveal a pattern, which can then be used as an applied decoration. Nerikomi designs provide a wonderful way to work three dimensionally with patterns and images. The results reflect a combination of both careful planning and accidental surprise, plus it's exciting work for those who love patterns and are drawn to the wet-clay stage of pottery making.
Here are a couple more examples with far less annoying music. The agate pottery revealed after firing the glaze is especially nice:
• Centuries old pottery gets new layer (YouTube / NHK WORLD-JAPAN)