Paint marbling is a contemporary technique with a long history. What started hundreds of years ago as the Japanese ink-based art of suminagashi has evolved into a fun, modern art form that's popular on YouTube and has been hailed as a trend by The New York Times. Nowadays, paint marbling uses a base of thickened water, onto which paint or another medium is poured and then swirled. Dipping paper directly into the paint creates beautiful, abstract art...