This is a knife sheath designed to fit a Shun Classic 8" Chef's Knife. I've included 3 versions:
1 - My original design featuring slanted "vents"
2 - An updated design which places a round "port" to display the knife's Shun logo
3 - A customized version that I printed for myself with an 'R' monogram
It is possible to print the original design without supports in a vertical orientation. However, when I attempted this, the resulting print was weak (due to the orientation of the layers).
Printing it in a spine down orientation will require some supports... but it turns out nicely.
Obtaining a "Goldie-Locks" fit: not too loose - not too tight - just right.
If you print this with PLA... you can warm the resulting print in HOT (near boiling) water to temporarily soften the material. Doing this allows you to insert the knife into the flexible sheath. Then (with the knife still inserted) you can run the print under cold water, it will re-harden around the knife. The result is a perfectly snug fit.
SVG Import Makes Shape Matching Easy
To design this - I imported an SVG (Scalable Vector Graphic) profile of my knife's blade into TinkerCAD. Once there, it was a simple task to resize the resulting shape to match my knife and modify that shape however I wanted.
Making an SVG file is easier than you might think. There are free online image converters that will take any photo and convert it to an SVG... done.