An inkstone / a writing brush / paper / a sumi is a minimum necessary tool and, in the case of calligraphy with a writing brush, is called "study four treasures"
A sumi is necessary for water in the case of a solid sumi. In addition, sheets of plastic called carpet are overused. But the material isn't plastic.

inkstone

It's the same as a palette in a picture. To serve the ink ,or stock India ink. Building stones are usually used.

writing brush

Commonly,be used hair of animals such as a horse, a sheep, a raccoon dog,or use a cock, a weasel, a mongoose, a peacock. The grip use by tree and bamboo.