The 3motion system enables the recognition of gestures based on 3D trajectories in space. It consists of both a software and a hardware component. The Software Development Kit (SDK) enables programmers to implement and control how they want to recognise movements in space such as a punch, a golf swing, a baseball pitch or even a dance move. Although the SDK can work with any positioning device from a 2D mouse to a 6 degree of freedom tracker we have developed our own low-cost hardware to provide wide-range wireless functionality. The main innovation of the 3motion system is the combination of a 3D curve matching algorithm with acceleration signatures from inexpensive inertial sensors.