obviously its not going to be as involved as the actually favelas, I need room to actually move stuff

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I am more or less thinking about the density from CoD. a couple of openish spaces, lots of windows, ladders, 2 or 3 multi level buildings and some roof top terrain like arials, water tubs, some catwalks etc.
Now I just need to go through my terrain box and work out what I already have and then where to get foamcore...
I think alot of Balsa is also in order with corrugated cardboard.
EDIT:
I'm also thinking of making it modular (maybe six 2'x2' boards).