I don't think I've seen anything like that before, so I decided to share it with you. This book has a cardboard front cover... and a soft back cover, made with the extension of the marbled paper turned over the spine.
Some of the volumes about book history are marvelous samples of book craft themselves. That's the case with the work of German manufacturer and researcher of paper Armin Renker Das Buch vom Papier.
I first saw this engraving in a book published to celebrate the fiftieth anniversary of the Netherlands Association of Antiquarian Booksellers. However, its story seems to be not as simple as the text below the picture states.