The controllable growth of a periodic hexagonal array of ZnO microrods and linear arrays of ZnO microtunnels has been demonstrated using hydrothermal synthesis and channel stamping. ZnO walls (see figure) are formed from a solution containing Zn(NO3)2-6 H2O at pH 10.9 for 24 h at 90-degrees C. The controlled growth of these ZnO crystals is expected to have great potential for biosensing, optical emission, and ultrasonic imaging applications.