Uses a passive pickup system but with a few twists. Toggle switches select the bridge or neck pickup and add one of two (or none) capacitors in parallel to change the resonant frequency. Also decided on a simple mute switch in lieu of a volume control.
The external battery powers the fan and light, controlled by the red push buttons.
I've also rounded the back after removing the initial finish (nitro burns nicely), with a dremel, sandpaper and tons of elbow grease.