to the FSM forum, and to the hobby
There are a variety of products, as mentioned above. However, one other, cheap, method might be in order as well. Take some normal corrugated cardboard, and remove one of the top layers so that you can see the corrugations. Paint it thickly with white school glue, and allow to dry. You do this so that the cardboard will become harder. Then, take some thick aluminum foil, and pressit onto the cardboard, being careful not to collapse any of the bridges. Once done, you'll have a nice print to use.
If memory serves me right, a similar technique was used by one of the authors of TMMI for a diorama, and the effect was done very well. I'll see if I can dig up the mag for some details.