There are a lot a `self`s here.  It's feeling like a smell.  (Do smells have a feel?  Yuck.)  I guess `FactoryGirl` takes this approach, but it just seems weird to me.

Incidentally, if you did make these all instance methods, then `Smokestack::Factory::ClassMethods` could just be instance methods in `Smokestack::Factory`.  You could get rid of the `self.included`.  Simpler code and all that.