Materials scientists have struggled for a while to find a process which can be used to engineer individual grain boundaries separating two adjacent grains. Considerable effort has also been devoted to finding a technique that can control the orientation of individual grains. A temperature gradient applied during the chemical vapor deposition of thin copper films provides an effect such that chains of grains oriented in the same direction are produced at chosen positions in the film. As a result of an interaction between defect migration and crystal growth, interconnected grains, oriented in the ⟨110⟩ direction and separated by twin grain boundaries, form chains along contours of equal temperature. When the temperature gradient is small, low-angle tilt boundaries, low-energy coincidence-site boundaries, and twin boundaries are observed. For a sharp temperature gradient, all boundaries are coherent twin boundaries. ©1997 American Institute of Physics.