hi,
I find out a new technique to make a ruined bunker. First you take two pieces of flat polystyrene. You cut them into the right form and glue them together. After an hour, you put clay on it, just a thin layer. If this is dry you can see alotscours in it, Then you cover it with a black matt spray. If thats is done you can paint it.

Here are some photo's

Laurie :-) :-)

Sorry, couldn't see any images or links... I wonder about it, though, as I am about to make a diorama having a bunker in it.