I pulled this post from a PA gaming forum that I haunt, in an attempt to bring all my efforts under one roof.
The first step in building the world of TEOTWAWKI is to make some blasted ruins. I started with a laser cut foam core 6 story building from Gamecraft. With shipping it cost me $20. It might seem a little steep in price, unless you've ever build ruins from foam core. For me the money spent was worth it. I'll most likely post a review of this item in the near future. Here is is laid out on the table.
I then took and drew out my ruins and started cutting. I numbered the pieces, so they didn't get mixed up in the pile. In the end, I had very little in the way of unusable scrap material.
After I had the basic shapes cut out, I shaped them to look more like broken concrete and such. I ended up with 13 pieces total; 9 corners and 4 standing walls:
Here's a close up of some of the corner pieces in various stages: