Randy Parsons built him a copper painted Jet, which was the first draft, sort of. Jack liked it, but wanted to use real sheet copper, so Randy built him another one with the copper top. Judging from the other copper guitars Randy has built, and seeing some photos of the production of them, the copper is a sheet copper and is pretty thin. Maybe like a credit card. You know what is also about that thickness? The drum wrap Gretsch uses on the Sparkle Jet. Based on this, I would venture to guess that the Triple Jet that Jack used with the Raconteurs is a mahogany body and neck with a maple top and the sheet copper glued to the top and lacquered over.