Awesome job there Michael! Looks like a very simple yet great solution to the grinds going everywhere. I own a Rocky and get a little frustrated with the mess it makes as well and have been trying different mods etc to overcome some of the shortfalls - Funny how we are always looking for ways to improve our tools!
I might look into picking up a second hand one of these for my filter/plunger grinds as I also get sick of having to flush/clean between brews and then dial in again for the espresso. Happy with the grind quality?