If you want the look and feel of metal flashing, you can buy metal tape at the hardware store. It's about 2" wide and comes in a roll like duct tape. It's very thin aluminum and has an adhesive on the back side. I put the tape on card stock and then use my wafer dies just like usual.
I haven't seen any change in the way the dies cuts and I've used it with some very intricate Memory Box dies with great success. When you think about it, it's very similar to using tin foil in punches to clean and sharpen the edges.
By the way, the metal tape is a really shiny silver and makes great stars and jingle bells. I've also used it in Martha Stewart punches with no problems.