Dave, one of the owners of Fishs Eddy, made a fortuitous find on a recent buying trip to the Midwest: Vintage metal stationer's engraving blocks from the 1940's and 1950's! He came back with hundreds of initials and full addresses, most in their original boxes with handwritten names and dates of when they were last used.
I wrapped them in pages from old Anthropologie catalogs and adorned them with spare buttons.