I'm selling this Mixer on eBay Kleinanzeigen:

https://www.ebay-kleinanzeigen.de/s-anzeige/eurorack-matrix-mixer/2176962340-74-2149


I bought this mixer some while ago on eBay. It was made by a guy from Berlin (can't remember the name). He said it was one of his first attempts (if I remember correctly) and it it based on the doepfer diy circuits.