... seal the ends to prevent them from fraying.
Back to the book: As I didn't have the ebook here, i cut a piece of paper in the same size to arrange it on the inside at the back, to see where to put the elastic.
Something like one centimeter from the edge fittet here, so the ebook will be in the middle of the analog book, but there is enough space to glue the elastic on. Mark the edges with a pencil.
...and a second cut only a few millimeters parralell.
....to fit in the elastic nicely. Now measure it again, so it fits around the back of the book and into the slit on the other side. If you cut it, seal again with fire.
I secured the ends to make them easier to glue on and safer to stay there with a little piece of paper and a stapler.
...on both sides. Then put glue on the whole page and close it !
Put the elastic around the side (you can see it in the picture) and put pressure on it! Only heavy books might be enough also, but i could borrow screw-clamps from my flatmate to put some extra pressure on it. Let it dry really good again, before you go on with the last part !