The paper explores the possibility of using periodic precipitation to prepare anisotropic materials, on the basis of a numerical model of the time evolution and product distribution in periodic precipitates formed by competitive particle growth. The model envisages a pre-existing uniformly distributed material. After a time which depends on the sample length and other system parameters, a nearly stationary state is reached, in which the band spacings and masses, and the radii of individual particles are indeed much more uniform than they are in systems which depend primarily on reagent diffusion.