At an antiques mall, I encountered a piece of Hamilton Mfg. Co. furniture I’ve never seen before. It didn’t seem type-related, because it was flat wood. Metal or stones are typically used for type galleys.
One of the staffers tried to help me find more information, but we were stymied. I took more photos and did more research to discover this was a rack of press boards used in book binding.
The metal rim on four side is screwed in to help reduce warping. The boards are used when putting a book in a nipping press on top and bottom of a bound and glued book with the lip in the space between spine and book cover with a case bound (hard cover) book.