1. Fold the paper in half along two diagonal lines, and then unfold it, leaving two crossed creases.

2. Fold the left and right corners of the paper to the middle, so that the vertices of both corners fall in the center of the square.

3. Fold the upper corner to the middle, so that the vertex of the corner also falls at the midpoint, and then unfold it, leaving a crease on it, and the small square has two diagonal creases.

4. Fold the lower corner upward, so that the vertex of the corner falls on the intersection of the two diagonal creases above, and then unfold it, leaving a crease, which has an intersection with the diagonal of the square.

5. Fold the lower corner upward again, so that the vertex of the corner falls on the intersection point just obtained.

6. Fold the lower isosceles trapezoid on the left and right sides to the middle and stick it on the crease obtained in the fourth step, and then fully unfold the lower part.

7. Fold up along the bottom horizontal crease to form a small triangle.

8. Fold the paper up and inward along the crease below, so that there is a small square shape in front of the harvest.

9. Fold up the lower folded part along the crease obtained in step 4.

10. Fold down the upper part of the folded part just now, so that the small square is completely exposed.

1 1. Pull out the left and right corners to cover the bottom, and a bow-like shape appears.

12. Fold the appropriate part of the upper corner to form a small triangle.

13. Put a letter in, fold down the upper part and put it under the square in the middle, and a bow envelope will be finished.