Book Key

Have you ever watched one of those movies where someone just pulls a normal-looking book out of a bookshelf, and then a secret door opens?Do you want something amazing like that in your Minecraft world? Well here ya go!

I didn't put any text to explain anything in this video because I felt like it wasn't needed.Just incase you guys aren't completely sure how this works:

When a minecart is on a detector rail, you can put a comparator next to the rail and it'll treat the minecart like a chest.The amount of items in the cart determines the strength of the signal the comparator outputs.However, some items give a stronger signals than others.In this case, the book and quill gives a higher strength than the written books.So if you pull anything except the book and quill out, the signal wouldn't be affected enough for the redstone to turn off, thus the torch turning on.

If you rename a hopper cart, when you click on it, you'll see it's new name(bookshelf) and if you put a block over it, you can still click the hopper cart.

If you manage to make it so that a decent amount(can be less than half, it seems) of a hopper cart goes above a detector rail, the detector rail will detect the cart(which is amazing).This is how the entire system works.The two furnace carts are there to position the hopper cart in such a position.