My grandfather, Dr. Pavel Katz, was a book and print collector in Prague between the two World Wars, and I suspect that my grandmother, Dr. Bozena Katzova, was one too. When they escaped after Hitler's invasion in 1938, they converted everything they were allowed to take with them into a bookplate and print collection. They bought themselves medical degrees in Bolivia with some of the collection. Most of the remainder of the collection was sold after the end of the war in New York so that my grandparents could get medical degrees in the USA (this time by taking classes rather than by bribing people), but a few of the dregs survive, carefully preserved in tissue paper in a few flat boxes in my loft. Now and then I take them out and gloat.
Here's a bookplate sheet I made some years ago, back when my surname was Loyd. I print them on regular computer paper, cut them out, and rubber cement them onto the first page: