The grapevine motif was printed using ABS filament on acrylic sheet. As we discovered a while back, the ABS/acrylic combo has great stick properties and is almost impossible to release, which is perfect for this application.
After the print finished I laid a sheet of annealed copper over it and embossed it under a 40 ton hydraulic press using a urethane conforming die.
You can see signs made using this technique at http://www.copperimpressons.com
This thing was featured on the 3D Printing Today podcast available on iTunes, Stitcher radio or direct from the source at http://threedprintingtoday.libsyn.com/