I'm pretty new to modding and I would like to create a mod in which every world has its unique set of items/blocks. I already have a way of creating a new random set of items and blocks (specifically a material, an ore for that material, and a set of tools for that material) every time I launch minecraft, but this set is destroyed and then recreated (with different names, durabilty, ecc) when relaunched. I would like a way of attaching this random set to the world in which it has been created (actually I would need help with creating the set upon the creation of the world instead of the minecraft launch too because just running the code in the eventHandler net.minecraftforge.event.world.WorldEvent.CreateSpawnPosition doesn't seem to work; I think this has something to do with registries/preInit-Init-postInit but I'm not sure) so that the next time that I open that specific world the items are the same as before. Every bit of help is welcome and if I haven't been clear or you need extra information for answering you just have to ask.