buy blank cards...either blank face (if you're gaffing the faces) or blank backs (if you're gaffing the backs)...or double blanks (if you're gaffing both sides).
If you have Versatile Monte & Beyond, he teaches you how to remove the finish, and then to put it back on after printing your cards....I've made several black & white gaffs this way, and they turned out amazing. It's doing it in colour that I've got issues with (using my ink jet....B&W was on my laser, which was fine).