What is the best material for divination of the Holy Grail?

Bamboo, wood and other materials. The holy grail divination is also called the holy grail, cup, etc. They are made of bamboo, wood and other materials. The two hexagrams are three-dimensional crescent-shaped, each called a branch, with a front and a back. The flat part is called the "front side" (also called the front side), and the convex part is called the "negative side" (also called the back side).