http://www.musicfromouterspace.com . There you can find lots of great analog synth projects for varying skill levels. This one is the WSG, the Wierd Sound Generator. I ordered the printed circuit board from Ray and it was sent all the way to New Zealand in a nice timely fashion.
The build itself was pretty easy, the board wasn't hard to populate and I managed to fit the whole thing into an old cassette carry case that I found at an OpShop for 50 cents.
The hardest part was the wiring of all those potentiometers. It wasn't so much difficult as it was time consuming, but you definitely get a better result in the resulting sound when you take your time and do a tidy job of the wiring connections.