Almost all my sunken flat roofs, balconies, floor levels, and bases for terrain are made on formica. It cuts with scissors like paper, won't ever warp, and is super cheap (88 cents to a buck twenty nine for a 12" by 12" peice)
Super glue or PVA works perfectly too.
And you can get wood textures, including some that are in scale with 15mm and 28mm (weird, but true). And the stone textures are great for adobe roofs.
GREAT for making doors, too. the back, (underside) of the formica is a textured wood grain.
It is THIN, 110 weight cardstock thickness, perfect for basing a building and such.
Next visit to Lowes or Home Depot, look in "Kitchens", and grab a sample (the samples come in 2x3 inch, and 3 by five inch pieces)
You WILL find much use for Formica, I'll tell you what!
Cut out a base shape, put on some acryllic paint and cover with sand, let dry, overcoat with a watered down pain, wash and drybrush, and you have your best desert terrain ever for a base. (not for figures, but for trees and plants, a market kiosk, a tent, a load of supplies, whatever.)
I'm doing the final touches on "Not Khartoum" and knee deep in formica now, so this is a good time to spread the word!
Thanks for listening, droogs.