Why is Nanjing paper-cut called one of the three treasures in Nanjing?

Nanjing paper-cut belongs to a branch of Jiangnan paper-cut. Nanjing paper-cut is characterized by flowers in flowers, questions in topics, rough details and mental stupidity. At present, Nanjing paper-cutting is not only a national intangible project, but also a UN intangible project. Master Zhang Fang Lin, a representative figure, is the second generation descendant of "Jinling Sword Palm", a national non-genetic inheritor of Nanjing paper-cutting, and a researcher-level arts and crafts artist.