Going through the increasingly entertaining Synth Pool on Flickr, I found this picture of the homemade synth played by Nick Collier from Pink Grease. It's huge and flat and very analog, with some kind of ribbon controller instead of a keyboard.
You can see another (very cool) creation here. It seems he was helped out by Pete Hartley, a Sheffield legend who runs a little shop, Hartley Electric Music, that makes and repairs all kinds of stuff. Pete sold synths to Cabaret Voltaire and the Human League, then apparently went on to design the Simmons-based drum kit which Def Leppard drummer Rick Allen used after losing his arm. Several websites also claim he built the guitar amp that Eddie Van Halen used to record the solo on 'Beat It', which seems unlikely. Perhaps they're getting him confused with Hartley Peavey...
UPDATE: Nick Collier now has a whole mountain of crazy new synths, at Nick's World of Sythesisers. (via Deviant Synth)