Module is available as a DIY project only.
No info about availability.
Mixer
The Mix is a DIY kit for a simple 3 channel mixer, but a great one to have! It is designed to sit next to the Grains, boosting the output of the Grains up to modular level.
It is easy to build – it only contains a few parts.
The Mix has a huge gain stage so you can use it as an external input for your modular too. To limit the output to -5/5V pp I added 2 clipping diodes which can be bypassed with the provided jumper. If you don’t want too much gain you can build the Mix to work as a normal 1× gain mixer just by changing some resistors (which are included in the package).
These merchants probably sell this module. Huh?