Funny I was just working on this this morning looking for a simple solution for my students.It kind of works. The third pot interferes with the other two and when I modified to code to add a fourth it interfers or doesn't work at all. Seems to be something to do with the map function Arduino code not workign correctly because when I poll [comport] with [print] each analogRead seems to be on it's own "channel". I can't figure out how to separate them any better than using [split] with there mapped values (not great). I tried [unpack] and [route] but neither of these separate the data streams.
On the hardware side I just have each 10k pot wiper connected it's own analog pin on the Uno and each pot is powered and grounded from the Uno via the rails on my breadboard. I'm guessing but adding in some resistors might stabilise the circuit a bit, I don't know if this would help with the interference or not.