Button powered enchant level select

Update: I have modified it so that the main redstone unit is one block narrower, one block lower from ground level and uses one less redstone repeater which makes lowering all bookshelves one tick faster. I have also included a link to a world download for those of you who don't want to use MCEdit.

Allows you to use buttons to select how many bookshelves are around the enchantment table which effects the available enchantment levels.

Stone buttons raise bookshelves to it's location in the clockwise direction. Wooden buttons lower all of the bookshelves. The stone buttons in the corners can be on either of the two walls, it does not matter. In the background, redstone signal strength is used as the main mechanic to read and store user input.

Xisumavoid had mentioned in his tutorial world tour that a player on the hermitcraft server had made a button powered enchantment level selector, so I thought I would try it out myself. Here's a link to the video: http://youtu.be/dz0goEvcZgk

After completing this I found a video of an other version of the same tool, here is a link if you are interested: http://youtu.be/UYn2sfkCd2E

Let me know if you find a way to make this more compact :)