First clamp the books to be bound with boards, etc. , and then punch holes with an awl at equal distances.
Use a long rope, recognize a large needle at each end of the rope for easy insertion, and then pass the rope through the first eye to make the lengths of the ropes on both sides equal.
One end of the rope goes around the top of the book and returns through the original eye, while the other end goes around the side of the book and returns through the original eye.
Then both ends penetrate into the same eye below, and at the same time bypass from the side to return, and then go down.
Pay attention when sticking out your eyes: the first eye should be equidistant from the top and side of the book, and it will look good if you put on a string, and it is square. So is the last eye.
You can use a line of paper or a notebook with holes to do the exercises.