Making realistic limestone bricks

I am trying to model a building that has large cornerstone limestone bricks at each corner placed vertically. I estimated them to be roughly 5 feet wide and 3 feet high. I plan to build this in NScale. This converts to roughly 1/2" wide bricks. Since these bricks are for each corner of the building I first thought I could use an L shaped piece of styrene but cannot find one that wide. Does anyone have a suggestion on how to make these large bricks? There are some styrene parts available but the bricks seem to be smaller than I need.

You could try a hot wire/knife to cut foam (pink/blue) to the size you want. It is easily carved/scribed for mortar lines, you can sand it if needed, paint it. The foam is pretty versital stuff.

Good luck,

Thanks. I found this resource: http://www.generalplastics.com/products/product_detail.php?pid=19&

OK now you gave me more ideas. I found that balsa foam is a good product. Has anyone used it? http://www.dickblick.com/products/balsa-foam/