Anyone involved in 3D printing/additive manufacturing (AM) knows about STL file formats. Problem is—and no offense meant—STL is dumb. It’s just a large text file, generally written in ASCII programming language, defining the surface of a closed solid using a zillion triangles. For every tiny triangle, the file lists Cartesian coordinates locating its three vertices plus a normal. You can slice it up to print, but that’s it.

STL files cannot include any information about desired color, desired material, surface texture, internal density gradient, internal fine structure, or other parameters that could be highly useful. So, some years ago several groups with smart, forward-thinking members began developing smart, forward-looking file formats for just this purpose. The two main versions are AMF and 3MF; this article will describe features of the 3D modeling format, 3MF.

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