Impact force is an important dimension for percussive musical instruments such as the piano. We explore three possible mechanisms how to get impact forces on mobile multi-touch devices: using built-in accelerometers, the pressure sensing capability of Android phones, and external force sensing resistors. We find that accelerometers are difficult to control for this purpose. Android’s pressure sensing shows some promise, especially when combined with augmented playing technique. Force sensing resistors can offer good dynamic resolution but this technology is not currently offered in commodity devices and proper coupling of the sensor with the applied impact is difficult.