Quatrain is available from my Etsy store here.

Quatrain is a 4 x 4 passive matrix mixer that can be used alone or installed into a Eurorack case.

It features 8 inputs (4 fixed and 4 switched) and linked attenuators for 8 of the 16 pots.
It can be used to mix control voltages, audio or create feedback paths and even a sequencer when used with other equipment.
The back plate doubles up as a blank panel when used in your Eurorack.
Blank panel designed by Jack_Sl0w