FritzFon C4 Case Replacement

A replacement part for the AVM Fritz!Fon C4 rear housing cover. The "*_iftest.stl"-file is just a slice to test the interface before you print in full resolution.

This is work in progress. While it fits well in two of my docking stations it's not (yet) a perfect form fit because the radii are hard to measure. Maybe i'll drop an update on that here later.