An axial field rotary energy device can include a housing having coupling structures configured to mechanically couple the housing to a second housing of a second module. In addition, the housing can include electrical elements configured to electrically couple the housing to the second housing. A rotor can be rotatably mounted to the housing. The rotor can include an axis and a magnet. A stator can be mounted to the housing coaxially with the rotor. The stator can include a printed circuit board (PCB) having a PCB layer comprising a coil.