This Demonstration is a tool for the visualization of crystal structures, showing either the unit cell or a periodic repetition. You can also add periodically duplicate atoms at the cell edges, which means that atoms located close to the cell boundaries are copied to the opposite side (where the next atom of the same type would be in a periodic solid). You can choose a variety of layout choices for atoms, bonds, cell outlines, and arrows. For a wireframe plot, set all atom radii to 0; to disable bonds, set the maximum bond distance to 0. The cell outlines and arrows can be manipulated to show the unit cell or the periodically repeated supercell.