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: 0.5–3.0 mm. Pick the one that matches your board (or the closest fit) and print it. I used PLA on a Bambu X1C at 0.16 mm layer height — nothing exotic needed.