I need to create about 500 square feet worth of windows with panes. Maybe with a grungy old factory look to them. The windows will be 3'-4' wide up to 8' tall. Plexiglass ain't cheap. The windows can be clear, but have a dirty look or even frosted. A person doesn't really need to see through them as long as they look like a window from the outside from a few feet away up to a couple hundred feet away.

Any ideas, tips, or techniques on what a person could do? I never messed with something like this...