Self-building Wall

A new design, of a 26 blocks wide wall of cobblestone, press the button and it automaticly starts building.
If a creeper explodes or tnt explodes, the wall will repair itself.
It's a very easy design, and I don't want comments that it's too easy or something, For more designs (like a self building house, bridge. you can look on my Planet Minecraft Channel.

For example, this design is very handy to place for of them around my self building house, no creeper will destory your house. It re-builds itself :)

Also in this design, most redstone is underground ;)

How to create a cobblestone or smooth stone generator: Youtube Video

Additional Notes

Please leave a comment and tell me what to improve ;)