A mechanism to select an area and replace block x with block y
- mark out an area like usual and place a builder
- instead of placing a blueprint or template, you place the target block
- It scans the area for the target block, and makes a temp in-memory blueprint of it (every other block is air, excavate turned off)
- Replace the target block with the desired block (whatever is in inventory) or a specified block (second slot next to target block)
- From here do everything the builder normally does, using the in-memory blueprint instead
use cases: In 1.7.10, a quarry can get jammed between the initial clearing phase and the mining phase if sand / gravel falls into the area. A replacer could be used before hand to replace sand and gravel with cobble, and then place the quarry and it will not be interrupted.
Can also be used for machines. You build a smelter with cobble pipe when you first start up. Later you have extra gold and want to upgrade it. Select the area with landmarks, put down the builder, place cobble pipe in the first spot, and gold pipe in the second and give it a bunch of gold pipe.