All the GAMGI functionality related with atomic structures with periodic boundary conditions is handled by cell objects. Crystalline structures can be created indicating either a crystalline lattice and a motif or a space group and an asymmetric unit. The 14 Bravais lattices can be represented by Conventional, Primitive and Wigner-Seitz cells, plus Rhombus and Sphere volumes. Users can choose the number of cells, the volume size, the cell positioning, the type of cell borders, solid or wired cell representations, and the cell color. Any Cluster, Molecule, Group, Atom or even Orbital, Text object can be used as a valid motif to construct a periodic structure. GAMGI provides powerful yet simple pattern rules to indicate which lattice nodes should be filled, this way allowing users to create complex mixed structures that can be used to study liquids and other non-periodic systems. In particular, these pattern rules can be used to build 2D and 1D periodic and non-periodic structures.