© 2018 IEEE. The facile preparation and optical properties of highly-ordered sliver nanostructure arrays with controlled pore-shape and size is described. The arrays were prepared via sphere-imprinted polymer (PDMS) templating which provided a versatile and reproducible means of creating periodic metallic arrays, over a large surface area of about l cm2, with pore sizes ranging between 430nm to 820nm. More importantly, the flexibility of the PDMS polymer allows for a range of pore-shapes - from spherical to cuboid - to be fabricated by template stretching. Diffuse reflectance obtained from the final Ag nano-structures indicated that the maximum surface-plasmon-resonance peak occurs at wavelengths comparable in size to the pitch of the arrays. Features in the reflectance spectra of the cuboid nano-pore arrays, on the other hand, bore little correlation with the pore sizes, but are general broader and more red shifted compared to the corresponding spherical-pore ones. Lastly, SERS spectra of 1-benzenethiol measured with these arrays revealed the major plasmonic enhancements to be attributable to surface nano-roughness with only moderate contribution from the periodically-corrugated structures. FDTD studies of nanostructures are also included, providing insights into the various factors crucially affecting a SERS experiment.