Bofthem writes -
Etch. Press. Print. Want to learn how to emboss paper for your own business cards? Create your own pattern on the computer, and etch it into a brass plate. I’ve wanted to make my own embossed business cards since I was handed a really incredible one at a fancy restaurant. I tried several methods of achieving the effect (photoemulsion, electrolytic etching) but ended up having the most success with a pretty simple and straightforward acid etch method similar to the one used in home printed circuit boards. I still have to work out a few kinks (such as flattening the paper after the emboss without distortion, or reorganizing the method to print before embossing) but I hope you can take something useful from my experiments, and apply it to your own projects.
HOW TO – Make your own embossed business cards using acid etching – Link.