I DIYed myself a few simple 1U modules. From left to right: A switched mult. The middle switch lets me connect the upper left bus to either the right upper or lower bus (yes, four or fife connectors per side would have been better…). Then we have a little voltage subtractor, great to generate a “ducking envelope” from a kick drum through an envelope follower. And last but not least a “precision” voltage adder. Those are always a good thing to have in a rack, i think.