STL and parametric OpenSCAD model of a graphite sheet (a.k.a graphene). With the parameters in OpenSCAD file you can define the sizes of the carbon atoms and the bonds between them. Also the amount of honeycomb structures generated can be specified in the input parameters. Cutting the model to half (by setting parameter half=true) makes 3D-printing easier. Then you can print two of them and glue them together to get a fully 3D object.