This is a pretty simple redstone device I created. I tried Doxume's map, but it was a bit outdated and command blocks had grown smarter. I decided to make a working version, so I picked up the pieces of his device and fit them together with my own glue. I used only vanilla Minecraft redstone and command blocks (no third party software like MCEdit), and everything is supposed to work as it does. This was created in 1.7.4 and probably won't work for earlier versions (or later for you snapshotters). It is important you read the additional notes. They contain important information.

Additional Notes

I cannot stress enough that EVERYTHING works completely as it should (I tested it). If you are using a different version, I cannot help you. I will take the item out of your inventory and replace it. That is how it's supposed to work. Otherwise it won't. You can tinker all you like and use the design in your own inventions.

If you have any suggestions, please tell them to me. If you make a map that uses my design, please give me a link (also take a look at the copyright information id you make a map. It is IMPORTANT!