Practice 1: Take a piece of paper with a few layers and flatten it, then fold it like a fan, and finally fold it in half, tie a string underneath it, and then pull the top layer apart!
Practice two: take toilet paper like folding a fan back and forth 4-5 times in the middle of the folding line, tied dead, and then the toilet paper on both sides of a layer of uncovered, it became a small white flower.