Anyone who watches Futurama knows that Bender loves beer. They even used him to brew it in one episode. Well, you know that saying about how life imitates art? Yeah, this is definitely one of those cases.
Bender's body is made from medium-density fiberboard and covered in cardboard that's coated with fiberglass. The eyes, head, and feet are polystyrene balls cut in half, and the legs are PVC.
The 'brain' is a computer built from 70s and 80s parts, and old audio chips allow Bender to say pre-recorded phrases. The whole thing is connected to a remote control, which looks just like the remote from the show and makes him talk when you press a button.
You can find a very detailed description of the building process, along with tons more photos and circuit diagrams on the project page.