copper roof vent

Does anybody have a source for a kitchen roof mount exhaust fan? The kind that has the blower mounted on the roof. It needs to be copper. The one I need to replace is 18 wide by 32 long. I'm removing a shingle roof and replacing with a copper roof and want to install a new copper fan. I can't seam to find what I need. If all else fails I could make it using all the internal parts of the old one, but that would take time to do.

I checked that site out but that's not what Im looking for. I need a kitchen exhaust fan with the motor in the vent housing on the roof

http://www.volko.com/copperatticfan.htm

Got a feeling you're gonna build that one! Sorry.