How to make invisible walls

Ever wanted invisible walls for your adventuremap or for builds on your server?
Then you have to follow this tutorial for having invisible walls.

The Plugin
Voxelsniper is a Bukkit plugin. You can use it for many other things such as terraforming or fast building.
It can be downloaded here:http://dev.bukkit.org/bukkit-plugins/voxelsniper/.

The Idea
Well, invisible walls are just ladders. The idea behind this technique is to place them and break the blocks who are
behind them. In vanilla Minecraft, this isn't possible because there are blockupdates.

Blockupdates
Whenever a block changes its attributes, wether its visible or invisible, there is a blockupdate. This also happens with
the ladders when we break the blocks behind them. Thats why they also break when we break the block behind them.

The method
So, now we can prevent the blockupdate ingame with voxelsniper. To do this, we need to configurate the plugin.
First we do /b 0 in the chat to set the blocksize to 0. After that we do /v 0 to set the block to 0 (air).
Now we can do /b s mp in the chat to have the no-physics brush (I'd call that no blockupdate brush :P ).

Commands:
/b 0
/v 0
/b s mp

Now you can right-click the block that is behind the ladder with an arrow in your hand, and voilá! you got your
flying ladder. When you now look on the other side of it, the ladder is completely blank and it seems like you
have a invisible wall.

Other functions of the no-physics-brush
With the no-physics-brush you could make other great things for your maps or servers, like floating signs, floating sand or gravel for mountains or cliffs or other non-floating tiles like the anvil.

2nd technique: Stoplag
Another good technique is to use stoplag from WorldGuard. Stoplag simply stops blockupdates. You can activate it by typing /stoplag and deactivate it with /stoplag -c.

Have fun with it! :)