Well, I have been playing tons of super hostile lately, and I kept thinking how cool it would be if something was to happen once all wool was placed, so I built this. Its fairly simple, placing the wool in it's slot causes it to power a piston above, which triggers another to push glass down in front of it. Once all wool has been placed, and all glass is down, a redstone signal will be emitted from the top, which currently only opens an iron door (I'm sure you could use it for some sort of epic cinematic effect with fireworks or something.) Im going to be building my own adventure map soon, and I think this will be perfect. To expand it. simply cut off one wall, then copy it over exactly as it is seen. Have fun!