NBTStructureLib

Functions very similarly to jigsaw structures from modern versions of Minecraft, allowing for building complex randomised branching structures directly within your mod, without causing worldgen cascades or having to manually type out block IDs by hand.

Structures can be configured to spawn in any dimensions or biomes you choose.

Can be used to generate simple non-jigsaw structures too, enabling you to quickly replace any structures in your mod that are causing cascading issues.