Cube is set in a gigantic maze-like cube with thousands of different rooms that have various obstacles the characters have to deal with as they explore, but the movie had a tiny budget so they only built one room.

So what they did was build the room with removable panel walls that were different coloured gels. They simply swapped the panels from scene to scene so some rooms were red, some were blue, etc, and simple camera angles were enough to convince you the characters were travelling through this giant structure. Very cleverly done!