What I would like to do is make a two block tall bookshelf system that pops out of the floor that looks like this: x=two block tall bookshelf o = blank space e= enchanting table
[x][x][x][x] [x]
[x][o][o][o][x]
[x][o][e][o][x]
[x][o][o][o][x]
[x][x][x][x] [x]
Completely flush with the ground, no redstone above ground, that extends when powered and returns when power is cut off leaving no floating blocks. I've seen it done in minecraft showcases but can't figure out how to do it myself and haven't found a tutorial for it.