Available as an assembled Module and as a DIY project.
This Module is currently available.
Mini mixer and output
"The Oppitz Mini (named after a German Scientist) is the smaller brother of the (unreleased) Oppitz module. It is a 4HP, 3-channel Mixer and Output Module. It takes 3 mono audio signals and drives a line out and headphone out."
https://www.tindie.com/products/sluisbrinkie/sluisbrinkie-oppitz-mini/
