Flood Filler

This plugin adds flood-filling related commands to allow you to easily swap blocks in individual structures. It adds four new commands:

This command will take all the similar blocks connected to the one you're looking at, and convert them into the given block Id.
The second argument is the limit of recursive depth. It's set to be 5,000 by default, and you can crank it up to 20,000 if you feel like it.
The third argument is the "-d" tag. Adding this after the first two arguments will cause the flood algorithm to search along diagonals instead of just blocks adjacent to it.

Practically the same as the flood command, except it floods out from the block you're standing in instead of the block you're looking at.
Stand inside an enclosed, hollowed out structure to fill it up using this command.
If you leave any openings to the outside world, then the algorithm will leak out and you'll create a huge cloud. I'm completely serious. This command is really good at generating realistic clouds, but if you plan to use it for that, I suggest you use a much lower recursion limit than the default.

This command will hollow out any structure you're looking at as efficiently as possible.
If the first argument is not provided, it will by default hollow out the structure with air. However, it can be given optionally to fill the structure up with any block type.
The second argument is the same as before, the recursive limit.
The third argument, although also the same as before in principle, does something very different from in /flood. Normally this algorithm will take advantage of corners, and fill them up accordingly. Although efficient, it can look bad in certain cases. This tag will cause the program to be more wary of those corners, and produce a somewhat more aesthetically pleasing, if less efficient, finish.

This command will create a thin shell of the block id you give it around whatever structure you look at.
The first and second arguments are the same as before.
The tags, though, are different. The "-o" tag, when used, will cause the created shell to overwrite blocks in order to finish.
The "-s" tag will cause the program to stop generating a shell around it when it reaches a block off point from the block you started it at. I know that sounds confusing, but it doesn't really work right now either, so you shouldn't have to worry about it.

If you give too small of a recursive limit to the program, especially with larger structures, sometimes you'll experience some severe artifacting.
The "-s" tag for the /shell command doesn't always work.
Does not work with water or lava for whatever reason.

If you give too large of a recursive limit to the program, especially with larger structures, If you're computer's not powerful enough Java may run out of heap space in the process of the program and create some even more disturbing artifacting. It's all about finding the right balance. Or just sectioning off large areas of your construct for each use.
Oftentimes very, very, very slow. Especially when making clouds. Prepare to crash your server multiple times.