Finally I completed this project which was delayed again and again during a few years. After the huge mistake in the box I used some years ago I decided to use a cardboard box. It's neither waterproof nor fireproof but it's made of archival quality cardboard, same as used in museums. It's supposed to be a barrier for acid and at the same time it protect the inside from dust.
I made it by myself so I can fix the measures to the notebooks. It looks an easy work but I had big problems to bend the cardboard because I used a thick one. I left spare room for a few more notebooks to come.