  The solution of a boundary--value problem formulated for the Kretschmann
configuration shows that the phase speed of a surface--plasmon--polariton (SPP)
wave guided by the planar interface of a sufficiently thin metal film and a
sculptured thin film (STF) depends on the vapor incidence angle used while
fabricating the STF by physical vapor deposition. Furthermore, it may be
possible to engineer the phase speed by periodically varying the vapor
incidence angle. The phase speed of the SPP wave can be set by selecting higher
mean value and/or the modulation amplitude of the vapor incidence angle.
