This mod adds three flood fill commands analogous to the paint bucket tool in a photo editor. The flood fill algorithm is given starting coordinates and will search through all connected blocks matching the block at the starting coordinates. After finding all connected blocks, it replaces them with the block specified for the fill.
/flood is the basic flood fill command, taking starting coordinates and the block to place.
/flood <start: x y z> <block>
/floodbox takes two more coordinates for the corners of a rectangular bounding box to limit the search.
/floodbox <start: x y z> <from: x y z> <to: x y z> <block>
/floodplane limits the flood fill to a specific plane. This could be useful for filling the walls, floor, or ceiling of a building.
/floodplane <xy, yz, or xz> <start: x y z> <block>