knife sharpening util (20° angle)

This is a simple wedge that helps you grind your knife on a whetstone at an exact 20 degree angle.

I recommend to print a handful of those at different scales, so you always always one with an accurate size. (Using them as differently sized disposables is simpler than complicated adjustment mechanism).

Another tip: Add a strip of Tesa tape (adhesive tape) to the bottom, to prevent abrasion on the whetstone.