MONK is a Programmable Digital Synthesizer made from scratch using Arduino and PureData. The Arduino microcontroller acts as an input device, reading the values of six potentiometers and transferring the values via USB to a computer that runs PureData. In PureData, these values are passed to parameters that control sound, so the whole setup turns into a musical instrument. You may programme your own patches to completely change the device’s audio function, or even use it as a controller for other purposes (for example: graphics control or interactive applications). The featured video is a presentation of MONK’s main patch in action, while this blog post is a presentation of the system’s inner – workings. If you read on, you will find all the necessary information on how to build your own.