The Crazyflie is a tiny quadcopter often referred to as a nano-quad, built using the PCB itself as the frame. Developed solely by open source tools and designed with development in mind. E.g. we choose 0603 components (resistors & caps) over 0402 to make it easier to replace components. The voltage regulators are adjustable which makes it possible to change the digital and analog supply voltages simply by changing a couple of resistors.