randomwalker
WARNING: Even in singlenode worlds that are very small with 3 random walk generators the world size can easily reach 8GB or so. Please use caution when using this mod.
3d Random Walk Blocks in Minetest
Warning: for low end computers don't place too many blocks or it may cause lag.
Note: Generators tend to die out when they either "eat" each other or if they go too far away from the map into the ignore zone.