Great work there, I have started printing the R2D2 v3, I am confident with all the printing and assembly that's required but the Arduino set up is going to be a challenge with my Zero experience lol.
The dome magnetic mount system is one of my own design that fits Mr. Baddeley printed domes (well at least the R2, R5 and BT-1 domes). The electronics are connected through a MagTag by Ian Martin.