Optimal and highly efficient two-dimensional designs are constructed for correlated errors on the torus and in the plane. The technique uses the method of differences to produce series of connectable planar squares. Efficiency calculations for planner versions of the torus designs show that the torus approximation is very satisfactory.
"Two-Dimensional Design for Correlated Errors." Ann. Statist. 19 (4) 2160 - 2182, December, 1991. https://doi.org/10.1214/aos/1176348391