I've been designing this lately - the Shagpile - an envelope controlled double tracking/chorus pedal. Basically, instead of having an LFO control the clock speed of the second voice, it's controlled by a very wobbly envelope follower, so modulates in unpredictable ways rather than the smooth in-out of a chorus.
Two controls - flutter controls the gain of the envelope follower, taking it from barely a ripple to Clari-Not style huge wobbling. Tracking controls the delay time of the second voice, from barely-even-there to nearly a second later. When you strum chords with the tracking quite close and the flutter about halfway, it sounds a bit like a very wobbly chorus.
The single switch makes the second voice slide up in pitch or down in pitch.
Pics!
Just sent off for the second version of this in a prototype run, and they'll be for sale in the usual way and maybe even in a limited, full pedal version. Decal needs a little work, other than that I'm very happy with this oddball circuit.
No sound samples but you can hear it being played on all guitar parts in this tune:
