I think Dave hit it right - floor tiles cut into small blocks. But since I tend to be a little lazy, I recently made
a building foundation out of Dr. Ben's Baby Building Blocks. They appear to be little pieces of linoleum floor
tiles. They are about 1/8 by 1/4 by 1/2.
I used two diferent colors - grey and tan - then weathered with alcohol and shoe dye.
http://www.debenllc.com/servlet/the-121 ... ins/DetailI left them uneven and with a few gaps on purpose - this foundation will go under an old building.

- Dr. Ben's Foundation.jpg (94.78 KiB) Viewed 283 times
I don't know why the top of the blocks looks yellow - it is weathered the same and really looks about
like the sides. Jaime has'nt taught me enough about photography, I guess.