After having watched the evolution of a variety of cellular automata and developed a certain amount of theory regarding their behaviour, it is not only possible to begin to predict the behaviour of a previously unfamiliar automaton, but one also begins to feel that certain desired effects could be obtained if only certain changes were made in the rules of evolution. This is the beginning of automaton engineering, wherein automata are designed to order; at least within the limits of certain constraints. To do this job well, it is necessary to continue analyzing the structure of automata, particularly along the lines of formal structure theory, possible mappings between automata, and the possible embedment of one automaton in another.