Water and Ethanol - OpenSCAD generated from chemical SDF files

Summary Molecule structure STL files are generated by OpenSCAD, of which program is generated by "sdf2scad.perl" Perl script from NCBI PubChem database (3D SDF format files). Model generator Perl script & OpenSCAD subroutines are also included for somebody who would like to generate your own chemical files from SDF data, or tune model parameters (need Perl & OpenSCAD). Water (H2O) and Ethanol (C2H5OH, alcohol) are most basic molecule. I'll upload more complex molecule model. Feb. 22 2015: updated "sdf2scad.scad", "sdf2scad.perl": see instructions for history. On ethanol, I included separate "carbon" (black) and "non-carbon" (white) STL files for dual-extruder printers, but it becomes dirty because of contamination. So on my other works in this series I don't, however, the script is still capable generating separate files (see instructions for detail). See picture in "Caffeine and Melatonin" http://www.thingiverse.com/thing:690625: the melatonin is made using two materials, and contamination can be seen. On the other hand, the caffeine is made using single (white) filament, followed by painted. Instructions For 3D printing, at least x8 scaling is recommended, for the strength of "hydrogen bond." ::-)) If you make other chemical things (see my other works), applying the same scale is better - the 3D structure maybe chemically exact composition. Also you can get free SDF data of your favorite chemical material :-) from PubChem, convert with "sdf2scad.perl" (need Perl) into OpenSCAD format file, run OpenSCAD (need "sdf2scad.scad") and get STL file. See the Perl script for limitations. For some CAD/slicer softs, fixing models maybe required. Somebody who would like to make bigger model for chemical students, increase $fn ($fn can be defined in "sdf2scad.scad" script, depending to the size of atom ball) or define $fs (comment out defining $fn). To ease painting chemical model, I tried to separate the model into carbon (black filament) part and non-carbon (white filament with paint) part, for dual extruder 3D printer, but contaminating each other makes the model rather dirty. The "ethanol-c.stl" (carbon part) and "ethanol-xc.stl" (non-carbon part) are for that. If you generate your own .scad file as this, first set the variable "$isc = 0;" to generate non-carbon part, next "$isc = 1; $isxc = 0" to generate carbon part, run OpenSCAD twice for two .scad files. Feb. 22 2015: updated "sdf2scad.scad": adjusted parameters so that "non-manifoldness" error is solved (with my slicer). Feb. 22 2015: updated "sdf2scad.perl": supports triple hydrogen bond. Feb. 21 2015: updated "sdf2scad.scad": added S atom.