Once folded, a little powerfull bookend. Store flat or between books. Flat easy print.

Print with layerheigth of 0.2 (also 1st layer), infill 30%+.

For correct foldlines:

Nozzle 0.3 → perimeters = min. 6!
Nozzle 0.4 → perimeters = min. 4!
Nozzle 0.5 or 0.6 → perimeters = min. 3

Printed in PLA (PETG becomes most of the time brittle)