  We use minimal area metrics to generate all nonorientable string diagrams.
The surfaces in unoriented string theory have nontrivial open curves and
nontrivial closed curves whose neighborhoods are either annuli or Mobius
strips. We define a minimal area problem by imposing length conditions on open
curves and on annular closed curves only. We verify that the minimal area
conditions are respected by the sewing operations. The natural objects that
satisfy recursion relations involving the propagator, which performs both
orientable and nonorientable sewing, are classes of moduli spaces grouped by
Euler characteristic.
