Quick, Easy, Chillingly Cheap Walls
I'm creating a quick holding cell/dungeon in my office for this year's party. I'm not about to move my desk and all its contents out of the room (I think taking all my pictures down and clearing out most of my living room accessories is enough). SO I've created some really quick, easy and cheap walls.
They are simply large cardboard boxes flattened out (I left the bottom outside edge flaps attached. This allows it to stand on its own for the small wall seen here). I draw the outlines of the boards with black spray paint. Let it dry. Then take light coloured paint watered down a little, dip a brush in (removing some of the paint from the brush) and lightly drag the brush along each length of "board".
I take a $5.00 (well really, a $2.50 because I got 2 for $5) "scene setter" (plastic sheet with an image on it) and tape it to the cardboard. Voila. Dab a couple of nails on it, and you're done. It doesn't have to be perfect because it's a) in the background, and b) going to be in a darkened room. I now place these in front of my desk, shelves, whatever.