Here is an iPhone 6 Plus mount/holder/dock that can be glued to a GPS system such as the ("Any Car Phone) "Any Car Phone Dock" by azzeloof or "CD Slot iPhone Holder" by polygoo.
Each STL file is for a different purpose:
+Naked iPhone 6 Plus
+iPhone 6 Plus with an Agent18 Clear Case. (The clear case is 80mm wide and 9mm thick).
+iPhone 6 Plus with a CellBee Super Slim Hard Shell Case (The original case was measured to be 80.95mm wide x 10.25mm thick)
Notes:
The GPS mount for the Agent 18 Clear Case was designed from scratch, whereas the naked mount was designed based off of davidmus' "iPhone 6 Plus Stand"
UPDATE
iPhone 6 Plus Phone Mount (Agent18 Case) v2.stl
+slimmer design (thickness of the material is now 2mm instead of 4mm), slightly wider measurements make it easier to slide the phone in and out while still providing a secure/snug fit.
iPhone_6_Plus_Mount.stl | 4.0MB | |
iPhone_6_Plus_Phone_Mount_CellBee_Super_Slim_Hard_Shell.stl | 89.1KB | |
iPhone_6_Plus_Phone_Mount__Agent18_Case__v2.stl | 1.2MB |