Prusa Mini upgraded knob - XL style plus divot

I had a problem with my prusa mini knob accidentally rotating while clicking.  For example, I'd try to tweak the hot-end temp a degree or two during a delicate vase and as I clicked, the knob would rotate to ‘Change Filament’ instead.  

@nix had a genius idea of adding a divot to the end - which really cuts down on accidental rotations.

But I also liked the simplicity and minimalistic design of the Prusa XL knob.

This mixes those two ideas together.  I also added some more plastic to increase the weight a tiny bit. 

Added a divot and a little more weight to cut down on accidental rotations during click.