We developed and evaluated a new approach for constructing reproducible, “geologically realistic” heterogeneity for near-two-dimensional transmitted-light experiments. By using an apparatus with a computer-controlled arm, mixtures of sand were deposited in an experimental chamber through a tube. Mechanical segregation processes within the tube and the chamber led to stratification that mimicked that produced by sedimentary processes. By varying the arm speed, stratum thickness and angle could be controlled. By using different sand mixtures, the grain size at the top and bottom of a stratum could be varied. Through the use of carefully designed computer programs, a variety of reproducible microheterogeneous and macroheterogeneous structures could be produced. A spectral evaluation of 10 sample chambers produced with a single program showed negligible differences between sample chambers.