How to make a birthday hat

1, cut a piece of corrugated paper about 3 cm wide. ?

2. Cut gaps on both sides of the corrugated paper at a certain interval. ?

3. After cutting, grab it by hand and gently rub it at the fingertips to make the cut gap fluffy, as shown in the figure.

4. Fold the whole crumpled paper in half at the edge of the hat three times and staple it with a stapler.

5. At the gap, put a thin ribbon at every place and tie a knot in the gap to fix it.