I think I should have added that the idea is to add/subtract multiple input CVs together. I think your Func mostly scales/offsets single inputs, right?
What I am looking for is a way to add/subtract CVs from multiple sequencers (or sequencer rows) ‘on the fly’, to create more complex CV patterns from a few simple ones. Most of what I describe can be achieved by the Mtsch SUM module, which allows one to patch in multiple CVs and then for each toggle whether they should be added/muted/subtracted.
There are two things I would like to see different: The three-way switch is a bit cumbersome. It would be much easier to be able to switch back and forth, which as far as I can tell is not something that can be easily done in VCV Rack. Therefore, another option would be to instead have a two-way switch, and a separate mute button to disable the signal.
The second thing would just be nice to have, which is that unused inputs default to a value that can be set with a knob. This way, in addition to adding together the CVs from inputs, you could also transpose the resulting patterns by a certain voltage, for example to do octave switches.
None of this is impossible to do with existing modules, but it just requires patching various things together, while I would like to have a more elegant solution in one module, since I use it so often (to be clear, I have nothing against patching; in fact, it has become an addiction). Again, if no one else does it, I might just make one myself, because it is probably relatively easy to do, compared to something like creating a filter. I just know next to nothing about DSP, but I have plenty of experience with C++ to be able to make something.