I've been working on designing a distortion unit for Eurorack. The ones that I am currently aware of seem to be very aggressive and non-musical so I have decided to roll my own. Here's a quick video of the prototyping as it takes shape. The input in this case is a pure sine wave, used to demonstrate the extent of partial addition. The output is certainly much more complex but still remains musical, to my ears at least. The future development will likely take the form of a combination distortion/filter (Low Pass).