I am absolutely sure that your fine patron was made either in Ausburg or Nuremberg. The style of the bone inlay corresponds exactly to that on the wheel-lock puffers and guns characteristic of the late 1570's and 1580's. The iron parts were originally blued, with some of the bluing retained on the inside of the lid of your cartridge box.
It is true that some Saxon patrons were inlaid in the same style but they all usually open by shifting a button on the underside whereas your piece opens by pressing a button on the obverse side.
You're doing very well indeed!
All the best,
P.S. Could you post an image of that spanner seen in the background?