I may still be waiting for my 3D printer to arrive, but in the mean time, the components for my HUD were waiting in the mail box today!
It included a Rasberry Pi model 3 B, an Adafruit Feather Bluefruit (bluetooth enabled Feather development board) and some headers for the Bluefruit.

So now I’m ready to push forward with this project and get the electronics finalised.  Once the 3D printer arrives, then I can start working on housings for the electronics.  Lots to plan and lots to do!