2. Fold the square paper diagonally in half.

3. Then the left and right corners are folded in half again and unfolded.

4. Then divide the triangle into three parts.

5. The left corner is folded along the crease.

6. The right corner is also folded.

7. Then fold along the center line.

8. Fold in half along the center line again.

9. Draw a pattern.

10, trim along the line.

1 1, and then slowly unfold, and the hand-cut window grillage is completed.