1 Disassembly and Self-Reassembly in Periodic Nanostructures: a Face-Centered to Simple Cubic Transformation**

To form ordered replica structures, highly ordered colloidal crystals must be used as templates. A variety of methods exists to produce such templates.[1] Here they were prepared by very slow sedimentation of monodisperse PMMA spheres (synthesized according to literature procedures)[2] with extreme care taken to minimize perturbation. In detail, the colloidal dispersion was stored in a capped crystallization dish until the PMMA spheres had assembled at the bottom of the dish (ca. 1 month, depending on the thickness of the colloidal crystal). The resulting sediment was opalescent, indicating structural ordering on a bulk scale. Then the cap was removed partially and water was allowed to evaporate at ambient temperature (ca. 1–2 weeks). With water evaporation, PMMA spheres tended to pack more closely due to capillary forces and finally formed self-standing monolithic pieces of the colloidal crystal