Dave in Alaska carves guitars out of blocks of aluminium on a CNC machine. He's only built four so far, but is planning more. He'll also be selling the electronic plans, so you can plug a block of aluminium into your own CNC machine, and it will spit out a guitar body.
He's not the only person building guitars from aluminium. There's also Specimen, Industrial Guitars, Veleno, Zero and most famously Kramer, who made aluminium-necked (and generally out of tune) guitars in the '70s. (Thanks, Jack)