That's a Travis Bean TB-500.
Â
It's not a backplate, that is the neck of the guitar. The pickups are mounted to that aluminum base as well.
Â
Kevin Burkett makes amazing aluminum instruments. Electrical Guitar Company out of Florida. He uses the Travis Bean model as a jump off for his own creations, true to both their aesthetic and their construction.
Â
Go over to electricalaudio.com and search the forum. Lots of people saying lots of things about Travis Beans, EGCs, etc. It's also Steve Albini's recording studio and he's active with the commenting.