How to fold antique bookmarks?

1. First, prepare an antique cardboard and fold it diagonally into a triangle. After unfolding, you will get the following "X" crease pattern, as shown in the following figure:

2. Fold the upper left corner and the lower right corner to make them intersect with the "X" created in the previous step, as shown in the following figure:

3. Fold the paper in half to the left along the diagonal.

4. Rotate the paper so that the left and right corners are upward, which is consistent with the central vertical crease, and the following figure is obtained, as shown in the following figure:

5. Fold the upper left corner and the upper right corner of the bookmark bag, and unfold the bookmark with your nails, as shown in the following figure:

6. Finally, when you want to use an origami bookmark, just slide across the corner of the last page of the book. ?