A Floor stone.
Imagine a special block that forms the origin (0,0) of where a player may place/remove blocks in a flat space. Suggested range is (-9, -9) to (9,9), but I can work with more or less.
Using the item currently held active, it will place/remove blocks in a rectangle indicated by 2 numbers: The left and right distance of each line, and the top and bottom distance of each line.
Example:
I place a Floor Stone on my desired location.
While holding a Dirt block, I type '/floor 4 5'
Assuming from left to right, from top to bottom, A 9 X 11 rectangle of dirt is placed on to the the floor with the Z-axis of the floor stone, with the floor stone at the center of this rectangle.
It should stop at the first encounter of an error (like zero quantity, sector limits, town permissions, or another player's block)