replace

As title, We all like the pick/replace tool we have to removing and recolouring large sections of 1 block... ...But what about the other way around? We should be able to select a block (Preferably a list, or category of blocks) that will be "Protected" from removal by the build tool until...

Imagine building twice as fast as you do now with one simple tool. Hand held 'Replace' tool. In build mode or Astronaut-mode: point it at a block and that block is put back into personal inventory while a new (predetermined) block is installed to replace it. Instantly and simultaneously...