Well, I've finally finished what I started. After cutting up the bottle, I used duct tape to cover the sharp edges.
I cut out my pattern and used this cute bug fabric which I had left over from making a nappy bag for my son (when he was a baby). I cut 2 pieces right sides facing each other.
You then sew them up along the top and sides. Turn it inside out and it will make a snug cover for the book/paper holder. :-)