2. Fold the red paper in half once along two diagonal lines to form a triangle.
3. Fold the two acute angles of the triangle together to form a triangle.
4. Fold the triangle in half again along the middle line of an acute angle, so that the angle of 45 degrees becomes 22.5 degrees.
Draw a certain pattern on this triangle, which can be innovated appropriately.
6. After painting, use scissors to cut along the shadow part and cut off all the shadow parts.
7. It's still very nice after unfolding. If you fold and cut it with rectangular paper at first, it will become a long line, which is very beautiful.