Currently, custom items can be obtained and crafted in all worlds of a server. For some servers, this is not desirable. It would be nice if it were possible to add a whitelist or blacklist of worlds in which custom items can be crafted or dropped.

I have thought about this, and I don't think WorldGuard regions are very useful for this. Biomes can be interesting for block drops & mob drops, but I don't think they make much sense for blocking crafting.

This could be made even more powerful by allowing not only worlds, but also biomes or WorldGuard regions to affect drops.