I’m developing a matrix mixer I plan to have soon in the market with a few extra features for cv control and performance in mind. 4x4 mono, cv and proximity sensors controlable fuzz and VCA on one of the channels, cv out of the two proximity sensors, bi/unipolar function per column (to mix cv or invert audio), output gain pot with enough gain to bring line levels to modular, normalization to 5V on every input (3.5mm), ON-OFF-momentary switches everywhere, wall wart or extra long eurorack cable (included) to power it.
DIY or assembled.
Proto PCBs are on the way!
I’m also thinking on doing a stereo version of it. Having the PCB design already made should make easier to change a few components to turn it stereo.
I guess some people here may be interested 
Front panel prototype: