A while ago I made a set of 12 walls from the World Works Games' Mayhem Junkyard set. Each wall measures 6" long by 2" tall and they come in four different flavours. All walls are glued to bases that are 0.5" wide on either side.
The wall at the left of the photo above is a plain blank wall with no markings or graffiti on. I made six of these and two each of the other walls.
The wall at the right of the photo above bears a "Private Property" sign. It also has a very amusing poster that reads "NB Trespassing. Violators will be shot. Survivors will be shot again."
The wall at the left of the photo above has been spray painted with graffiti.
The wall at the right of the photo above has has numerous advertising posters stuck on it.
The photos directly above and below show the reverse side of the walls with their support columns.
All reverse sides of the walls are identical. These were incredibly easy to make. The walls and bases are reinforced with mounting card.