This is a really fun effect you can use by itself or with delay as in this example. It is easier on strats. I'm tuned down a half step if you want to play along. In the video there is a right hand view so you can see how I use my pinky to wrap around the volume control. Experiment with rolling the volume knob back to different degrees to alter the amount of volume change on the guitar. This guitar lick is just a little example so if you like the sound I'd encourage you to experiment with you own licks and see what kind of music you can create with this. A great example of a neo-classical style use of this was Ynqwie Malmsteen's "echo etude" on his awesome instructional video put out by REH.
