David has modified his radio to allow him to change frequency with no use in his fingers. He has a small Microair radio and he has essentially glued a piece of plastic around the size of a tooth-pick to the volume and frequency knobs so he can turn them by moving his whole hand versus his fingers.
Much of the gear in the aircraft is pneumatic powered and runs off a compressor and tank in the rear of the aircraft. Throttle is controlled by sucking and blowing on a tube with a solenoid, plus there's an electric trim and break lever. It's well thought out ! When he's with an instructor all air powered controls can be over-ridden by the instructor such as the throttle. Whilst the throttle is air activated, he can still operate it by hand if required. Also, the PTT switch he presses with his elbow.