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abstracts
Although introduced 30 years ago, cost and performance improvements have only recently made 3D printing affordable. The industry wide input file format for 3D printers incorporates explicit mesh - `STL' data. Molecules and crystal structures, when including symmetry, crystal morphologies, or crystal defects are encoded in the parametrical `CIF' syntax. Free software for converting directly CIF data to STL files has just been developed, available online [1]. First examples of printed 3D models from STL-files created with these programs include molecules of sucrose, herapathite [2a], caffeine, humulone [2b], an alpha-quartz crystal and its Japanese {112} twin or a brilliant cut diamond. Far more CIF encoded models are available, even open access. The Crystallography Open Database (COD) features over 245,000 entries and has recently developed into the world's premier open-access source for structures of small to medium unit cell-sized inorganic and molecular crystals [3a], complementing the well-established open-access Worldwide Protein Data Bank [3b]. The Cambridge Crystallographic Data Centre in the United Kingdom provides crystal structure data of small (organic) molecules free for bona fide research [3c]. Structural data on inorganic crystals, metals and alloys can be obtained free of charge from the Inorganic Material Database (AtomWork) [3d]. Related to the COD, the crystallographic open-access databases [3e] ("COD offspring") provide CIF data for interdisciplinary college education. With this basic infrastructure in place, any interested college educator may print out her or his favorite crystallographic structure model in 3D and use it in hands on class room demonstrations [3f].
abstracts
Crystallographic models of molecule and crystal structures, crystal morphologies, Bravais lattices, space and point group symmetries, highly local and extended crystal defects, ... can all be encoded in the Crystallographic Information Framework (CIF) file format. While 3D printing has been available for at least 20 years, cost and performance improvements have only recently made 3D printing practical for usage by college educators and the general public. There is also an industry wide 3D printing standard, the STL file format. Virtual reality freeware programs that include conversions from CIF to STL are openly available [1]. The more than 250,000 entries Crystallography Open Database (COD) has in recent years developed into the world's premier open-access source for CIFs of structures of small molecules and small to medium sized unit cell crystals [2]. The International Advisory Board of the COD also supports a related project [3a], which provides CIFs for interdisciplinary college education. Three of these "COD offspring" databases have started to provide for free downloads of STL files of small molecules, crystal morphologies, and grain boundaries [3b]. These 3D printing files were created directly from the CIFs in these databases. It is now up to interested college educators to develop new pedagogy in teaching crystallography on the basis of 3D models that can be printed out from these files. To facilitate further developments in this field, there is a web portal of open-access crystallography resources to which all interested college educators are invited to contribute [3c].
