Dan,
Sorry to hear about the problems printing metal on the 7900. From my personal experience, the 3880 will print fine, as long as you load it in the front feeder. When I print the material, I increase the platen gap to the widest and the prints look fine. The ink is VERY delicate when it comes out of the printer - the slightest touch of the printed surface will disturb the ink so make certain to put the print aside for an hour or two before spraying, which is mandatory to protect the print.