I was recently asked about compiling an algorithm, plane of best fit (PBF), to quantify and characterize the 3D character of molecules as described in Plane of Best Fit: A Novel Method to Characterize the Three-Dimensionality of Molecules, Nicholas C. Firth, Nathan Brown, and Julian Blagg, Journal of Chemical Information and Modeling 2012 52 (10), 2516-252 DOI. The source code is all available from the rdkit repository https://github.com/rdkit/rdkit/tree/master/Contrib/PBF.

The compilation had a slight glitch but full details are here.