  In this paper we study the Casimir force for a piston configuration in $R^3$
with one dimension being slightly curved and the other two infinite. We work
for two different cases with this setup. In the first, the piston is "free to
move" along a transverse dimension to the curved one and in the other case the
piston "moves" along the curved one. We find that the Casimir force has
opposite signs in the two cases. We also use a semi-analytic method to study
the Casimir energy and force. In addition we discuss some topics for the
aforementioned piston configuration in $R^3$ and for possible modifications
from extra dimensional manifolds.
