I'd like to be able to create an ore vein which only generates on the sides of caves. This would allow certain caves to be rich in certain ores, without affecting things beyond the cave wall. This would encourage caving over strip mining.

The best way to implement this would probably be an entry that can be added to any shape. When set to true, only ores that directly touch an air block would generate. Any block in solid stone would be skipped.

To make this more flexible, you could specify a block and ores would only generate if directly touching that block. This would be nice if, for example, you want normal copper ore to generate around a Geolyses ore geode. Since you can't use the isAir check, this might be worse on performance though.

I wonder if it's worth adding a system similar to minecraft's recipe conditions. This would certainly fit into that category, but if there are only going to be one or two special conditions it's probably better to leave it as a separate flag / check

Seems to be working :)