An area to be filled must be specified using Land Marks. At least four Land Marks must be used to specify a three-dimensional area for the Filler to work in. Right-click the Land Marks to create a red frame of the area, then place the Filler at one of the Land Marks. The Land Marks will pop out of the ground and a black and yellow frame will show the designated area.
2. GUI
One of six patterns must then be designated for the Filler to determine what to do with the specified area. This pattern must be input using only Bricks and/or Glass in the 3x3 grid of the GUI. An acceptable pattern will then show a special icon in the right of the GUI and on all sides of the Filler block itself. The lights on the top of the Filler will also turn green, indicating it is ready to be powered.
Newer versions of BuildCraft (like the one used in Monster 1.1.2) feature a GUI that allows direct selection of the pattern by toggling through a list, rather than using bricks and glass.
Patterns
Fill
Clear Area
Stair
Fills the area with blocks
Clears the area from all blocks
Creates a one block high staircase
Box
Flatten
Pyramid
Creates a "box" with walls, ceiling, and floor, leaving the interior empty.
Clears all blocks from the area, clears all blocks above it, and fills in open holes directly beneath it.
Creates a pyramid
3. Filling Resources
The bottom inventory is where the blocks are placed to be used to fill the space. Any placeable item block can be used to fill the area. This includes typical resources such as sand, dirt, and cobblestone, but even most machines, pipes, and wiring.
Finally, power the Filler with energy (RF) and it will work from the bottom, up. More power means the Filler will work faster. The lights on the top of the Filler will turn red to indicate that it is done with its task.