  We examine how cosmological expansion arises in a universe containing a
lattice of spinning black holes. We study averaged expansion properties as a
function of fundamental properties of the black holes, including the bare mass
of the black holes and black hole spin. We then explore how closely the
expansion properties correspond to properties of a corresponding
matter-dominated FLRW universe. As residual radiation present in the initial
data decays, we find good agreement with a matter-dominated FLRW solution, and
the effective density in the volume is well-described by the horizon mass of
the black hole.
