Corner Cutting Jig for Bookbinding

A simple jig for cutting clean 45-degree corners on book board. Slide the board into the slot, run a knife along the angled guide, and get a consistent mitered corner every time. No measuring, no marking.

The jig comes in six versions for common board thicknesses from 0.5mm to 3.0mm. Pick the one that matches your board (or the closest fit) and print it. I used PLA on a Bambu X1C at 0.16mm layer height — nothing exotic needed.