This is a simple, no supports needed sheath for the Victorinox boning knives below. I designed it for the rosewood handle one, not realizing the plastic molded handle is slightly different in shape, however it still works to keep the sharp edge protected from hands if you store in a drawer. There are a few dimples on the inside near the entrance to help with retention. If however it's too loose for your liking, just heat up the end ever so slightly and squeeze the sides together a little bit (with the knife out.)

I printed with PETG at 0.2 layer height. I'm sure other filaments would be fine as well, and a 0.28 layer height would probably work. You do NOT need supports for this if printed in the STL's orientation.

https://www.amazon.com/gp/product/B0019WX6H2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B001U57EJ4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1