It's a sort of tone generator. It's hand made by this guy:http://electrolobotomy.blogspot.pt/
I think these synths are a lot of fun, some reverb would do some serious drones!Thanks for posting.Los Bosques Sombríos I - Sonic Forest & Sylo Synth
Those are pretty interesting synths. I've been interested in the Folktek devices, http://folktek.com/ ,but they are kind of pricey. The Electric Lobotomy stuff is a lot more affordable. I may have to look into these more.
Most of the handmade synths I have played around with seem to be one trick ponies, which is fine if you like the one thing it does well. For me they just seem too limiting so I've never gotten any for my studio.