I made a guitar looping video using only my pedals not a guitar:
Here's how it works; the Zvex Fuzz Probe is in an auto oscillating setting. The note it produces is then altered with the Digitech Whammy and the Eventide Pitchfactor; along with reverb and stereo delay. Because the Pitchfactor in diatonic mode only jumps to notes in a certain key, I have some control over the melody.
The looper I'm using is the Digitech JamMan Stereo.