electro-harmonix's Pitch Fork polyphonic pitch shifter can make your 6-string guitar sing like it a 12- or 18-string guitar, emulate a synth, and get some truly unique sounds without glitches. Choose between single note pitch shifting or dual note (one up and one down) pitch shifting. It works great with bass, too, giving your bottom end even more bottom, and shimmer on the top! You can dial in almost any interval difference you want or use an expression pedal for real-time pitch control. Put a fuzz or distortion pedal in front of the Pitch Fork for synth-like tones and gritty lows.