I made a few new bookmarks and this time paid attention to the size so I could easily stick a piece of card on the back once I'd sewed the material on. I was a bit dubious about sticking two pieces of card together, it wouldn't look good if they pealed apart. I decided on PVA glue and smeared it out with my finger so I didn't get any gloopy bits squishing out the side. A few hours under a heavy pile of books and they were great. Much more sturdy than my first few where the card stock was a bit thin.
I think the coloured eyelets really finish them off nicely. In fact I liked the them so much I did the same to the earlier batch.