Here are some interesting patterns of door keysxabyzaz
Top left: Rather large pattern that oscillates a few times then closes completely.
Top middle: A smaller pattern, without the extra crates at the top it oscillates, with them it closes.
Middle (underneath the previous one): Another pattern that closes completely.
Top right and middle right: A pattern that oscillates normally, but with an extra half-speed stream of crates it either closes completely (top right) or opens completely (middle right)
Bottom right: Two diamond-shaped patterns that oscillate
Bottom left: (From left to right) A pattern that oscillates in four directions, A pattern that behaves strangely, and another pattern that oscillates in four directions.
I got these patterns by randomly placing door keys next to each other, so it's likely that other patterns do other interesting or unusual things.