I have been considering open sourcing my design for several years now. Likely the approach I would take is to provide a carrier board (not dissimilar to an Arduino shield) that handles all the power management, bluetooth, and GPS connections and allow people to manage their own wiring harness, battery selection, 3D printed cases etc. The firmware is all C++/Arduino so its pretty easy to get into. Having a single carrier board eliminates a lot of the headache around integrating all the different devices in different ways and allow everyone to work from a common connector standard (and base firmware...