  In this paper we study the (equivariant) topological types of a class of
3-dimensional closed manifolds (i.e., 3-dimensional small covers), each of
which admits a locally standard $(\mathbb{Z}_2)^3$-action such that its orbit
space is a simple convex 3-polytope. We introduce six equivariant operations on
3-dimensional small covers. These six operations are interesting because of
their combinatorial natures. Then we show that each 3-dimensional small cover
can be obtained from $\mathbb{R}P^3$ and $S^1\times\mathbb{R}P^2$ with certain
$(\mathbb{Z}_2)^3$-actions under these six operations. As an application, we
classify all 3-dimensional small covers up to $({\Bbb Z}_2)^3$-equivariant
unoriented cobordism.
