Fill an area with blocks: two corners, hollow/outline/destroy modes and a replace filter.
The /fill command fills a region with blocks — from a small rectangle to a whole room or floor.
It has several modes: hollow makes a hollow cube, outline keeps only the outer faces, destroy breaks existing blocks first, and keep fills only empty space.
One important limit: the game processes at most 32768 blocks at a time. Larger regions must be split, or the command needs an explicit per-tick limit.
Set the two corner points.
Choose the block and the fill mode.
Optionally set a filter block so only certain blocks are replaced.
Check the computed volume: above the limit the tool adds a per-tick limit component.
The region exceeds the built-in limit of 32768 blocks. Split the build into parts, or add a limit on blocks changed per tick.
Use the replace mode and set the filter to air. Existing blocks are then left alone.