I’m posting this partly in appreciation for the design that arh2 posted.
I’ve modified that design to have a double hinge and fold-over cover, held by magnets. I use the same notebooks that arh2 uses to put inside.
The keys to making this work are 1) use a kettle to steam the hinge as you slowly bend it, then let it cool and dry in the folded position, and 2) you have to experiment with your material to get the holes for the magnets the right depth. I used 500/full power to engrave the holes in proofgrade cherry ply. The photos show it done in medium draft board, which is about the same. The 6mm x 2mm magnets I got on Amazon.
