Or, you know, a piece of timber and some sand paper.

The consumer-grade 3d printers I have exposure to would have trouble with some combination of piece length, tensile consistency, strength and durability you'd want in a book press. Printing alone would take longer than sanding and drilling. And I suspect a printed part wouldn't be so forgiving of adjustments made after manufacture.

Using the 3d printer because it's fun and a learning experience is fine, but calling it "ideal" when it doesn't offer any real improvements over the cheaply and easily made "traditional" material is going a little bit too far :-).