level of difficulty:
Jeff Beck, Peter Frampton, Slash and Zakk Wylde have all used a talk box at one time or anothe to give a vocal quality to their solo guitar. A talk box is essentially a speaker attached with an air tight connection to a plastic tube. When you place this tube in your mouth it acts like an artifical larynx and you can make yor guitar speak. A vocal microphone next to your mouth then picks up the sound and feeds it into the PA system.
This project shows how you can make your own talk box using a pair of powered computer speakers, a rubber toilet plunger, duct tape and some vinyl hose. This talk box takes a line-level input, so you would need to connect it to a line-level output on your guitar amp (like a headphone out socket).