We study realizations of periodic graphs in Euclidean spaces with each
vertex in the center of gravity of its neighbors. As a first application,
we show that every planar, 3-connected, 2-periodic graph can be drawn
into the plane with convex faces such that the drawing realizes every
combinatorial automorphism of the graph as an isometric symmetry. This
extends results by Thomassen and by Mani-Levitska, Guigas, and Klee.