Preparation materials: Choose lighter paper, such as sky blue, and prepare a4 paper, watercolor pen, scissors, glue, etc.

Folding and coloring: Fold a4 paper into 15× 15cm, and color the two short sides of the paper with colored pens, paying attention to the color sequence of red, orange, yellow, green, cyan, blue and purple.

Folding and pasting: After painting, fold the paper in half four times in the middle, then open it and arrange it into a fan. Cover the left and right sides of the sector with double-sided tape and stick it.

Enrich greeting cards: you can cut paper of other colors, cut it into the size of the main greeting card, and stick it on the back of the main greeting card with glue as decoration. You can also write greetings or draw patterns on greeting cards.