For the past couple of months, I’ve been building myself a surveillance drone. My craft consists of a remotely controlled quadcopter – a small helicopter with four rotor blades that looks like a flying X – with an onboard video camera that sends a live feed back to my laptop base station. It also transmits telemetry data about its altitude, speed, bearing and location from its onboard global positioning system receiver. In future, I plan to equip the aircraft with an autopilot system that will allow it to fly from one GPS-specified location to another without my having to pilot it.