A novel nanostructured sandwich PAA/Al/PAA (PAA: porous anodic alumina) was successfully designed and fabricated by anodic oxidation on both sides of an Al foil. The pore size of the PAA membranes was controlled by choosing appropriate voltage, length of anodic oxidization time, temperature and electrolytes. The thickness of the central Al layer was varied by changing the anodic oxidization time. We show that the nanostructured sandwich PAA/Al/PAA can be used as a template in fabricating homogeneous or heterogeneous nanostructured sandwiches by depositing the same kind of material or different materials into the PAA membranes of the sandwich. We also show that it can be used to prepare nanowires and bipolar electrodes. In addition, Al nanosheets or Al nanowalls were produced by removing the PAA films completely or partially. Nanogaps between the PAA films were also formed by etching away the centre Al layer of the sandwich structures. The thickness of these nanosheets, nanowalls and nanogaps was controlled by choosing appropriate electrolytes and electrochemical parameters during the anodic oxidation of Al. All these nanostructures offer novel opportunities for both fundamental research and technological applications of low dimensional nanostructure systems.