Available as an assembled Module and as a DIY project.
This Module is currently available.
Multifunction Mixer
ami is a 3 channel mixer with additional inverter on one channel and dedicated output jacks by no problemo modules. The sum is using normalling to break the input to the sum when the single outputs are used.
Synthrotek AMIX DIY Kit
Abyss Devices aMix Four Channel Mixer
Abyss Devices aMix 4 channel 2hp
Eurorack Hardware AMIX - Active Audio