1. Cut the cardboard into rectangles with scissors, divide the cardboard into upper 8 cm, lower 8cm and middle 2cm with a ruler, and mark it with a gel pen.
2. Fold the cardboard in half along the horizontal line as shown in the figure.
3. Stick the double-sided adhesive tape to the top of the cardboard to make the upper and lower ends of the folded cardboard stick together.
4. Cut out the wave pattern with cardboard and stick it on the bottom of the desk calendar with double-sided adhesive.
5. Put the calendar cards drawn with colored pens and gel pens into the desk calendar, and the calendar will be completed.