This is a simple blade cover for the very well made Olfa Hobby Knife.
I designed this because i mistakenly bought a blade holder that came with the saws and no cover for the knife blades. Since I was designing something new I figured I'd add some features that helped prevent it from rolling more than Olfa's little nub they built into the handle and also made removing the cover easier.
The author marked this model as their own original creation.