  We consider three methods by which one can generate new cosmological models.
Two of these are based on the Lorentzian structure of spacetime. In a
Lorentzian manifold there can exist horizons that separate regions of spacetime
that can be interpreted as cosmological models from others that have the
character of ``black holes.'' A number of well known solutions of this type can
be used to generate both known cosmological models and others that do not seem
to have been recognized. Another method based on the Lorentzian character of
spacetime is to simply interchange some space variable with time and try to
restructure the metric to make a viable cosmology.
  A more broad-ranging method is the use of modern solution-generating
techniques to construct new models. This method has been widely used to
generate black hole solutions, but seems not to have been so widely used in
cosmology. We will discuss examples of all three methods.
