One more simple way ---You could make a reverse Xerox or other copy print in B&W. Then tranfer it to your metal surface by using an organic solvent like rubbing alcohol. Paint the solvent ON THE BACK of the xerox and, with the print surface down onto the metal surface, rub the design with a burnishing tool (like the back of a teaspoon)
It usually transfers quite easily . Perhaps you should scuff the metal a bit with a 6-to 1500 grit sandpaper.
The trick is th right solvent for the print