Going to holidays and need a way to safely transport knife (so you won't need to use dull ones in the place you are going to)? This simple and quick to print sheath will help! 

Takes less than an hour to print on Ender 3. Print on longer thin side, brim will be required. Recommend positioning it along Y axis, as in attached 3mf file. 

After printing it will be loose fit. But that's an easy fix: Turn on your heatbed to 60+ degrees and lie the sheath on its side. Once it gets warm enough to soften gently squeeze sides together and put the knife in. It should be perfect fit now :)