Minecraft Beta 1.7.3 Smooth stone slab/"Crash slab" generator

This is a Minecraft Beta 1.7.3 redstone contraption that can change a block&damage value through a glitch with pistons. It can change the color of wool for instance, but it also allows for creating smooth stone slabs without any need for inventory editing and whatnot. These smooth stone slabs also crash the game when hovered over in the inventory, which is what happened at the end of the video. (hence the name "crash slabs")