DF64 grind setting indicator

Another grind setting indicator for the DF64, this time with a new approach, combining my favourite aspects of the current crop of grind setting indicators :)

This one sits securely on the grinder, and can't be moved inadvertently. Additionally, I think it integrates nicely with the design of the grinder. I've done a bit of testing and refinement, but comments/tweaks are definitely welcomed.

(Picture is v0.1, a quick and dirty print to verify dimensions. Still need to print and test v0.2)