UPDATE: After doing some heavy testing I have discovered that the firmware build and params are lacking. I am in the process of creating a new build on a later version complete with lua scripts for indoor/outdoor operations. I will update this model when these tasks are complete.
This is the final revision of this build, I have enhanced it with a gen 10 GPS and a hotstart pigtail (see wiring diagrams) the earlier units suffered from problematic GPS performance because of the unit's small size and the proximity of the radios.
I have included everything that is required to get this drone setup including the custom built arducopter, hwdefs, params and microcontroller contents.
Note: that it's ok for the i2c multiplexor to sit at a slight angle.
Note: This thing is hard as hell to build, I did it partially as a challenge.
The author marked this model as their own original creation.