Here are some pictures of a little synthesizer I made.  It's made to hang below an electric guitar.  It 's designed around the Soundgin chip and is controlled by a Picaxe microcontroller.  I call it the WidStick.  Its sound can be modulated by moving your hand over the end of the tube.   Click the following link to hear a sample of one of the sounds it can make. widstick.wav
Here is a link to a YouTube video of a couple of other synths I made.  One of them is called the Electrocarina and it's a kind of electronic ocarina. The other is a violin-like instrument called a Fiddlestick.