Bone folder, approx. 123 mm long, 20 mm wide, and 5 mm thick. Its cross-section is elliptical. It is made of two halves, which are then glued together using super glue. Therefore, you must print the model twice. I used PETG with a 0.1 mm layer height.

Bone folders are used in bookbinding and paper crafts for folding paper. Despite its name, this one is not actually made from bone, but from plastic. :-)