  We present a theoretical and experimental analysis of circular-like orbits
made by a marble rolling on a warped spandex fabric. We show that the mass of
the fabric interior to the orbital path influences the motion of the marble in
a nontrivial way, and can even dominate the orbital characteristics. We also
compare a Kepler-like expression for such orbits to similar expressions for
orbits about a spherically-symmetric massive object in the presence of a
constant vacuum energy, as described by general relativity.
