The file 'Parametric Kitchen Knife Sheath (Improved Remix) 3D Printer Model' is (stl,scad) file type, size is 10.9KB.
Remix of Parametric Kitchen Knife Sheath by bikecyclist and vorpal (Steve Pendergrast)
Should work for any knife that is pointy at the end. (For non-pointy knives, guesstimate the length the blade would have if it had a point.)
There is an option to provide the sheath with "windows" so you can easily tell if the knife is serrated and has the shape you are looking for without unsheathing it. These windows are on alternate sides of the sheath to facilitate cleaning.
Update 1 June 2020:
Update 23 May 2018:
Kitchen_Knife_Sheath.stl | 106.6KB | |
Parametric_Kitchen_Knife_Sheath.scad | 5.9KB | |
Parametric_Kitchen_Knife_Sheath_V5.scad | 6.2KB |