A software package is described that operates on small molecules observed in the PDB collection of protein structures. Molecular topology files for many molecular modeling programs can be generated automatically. The three-dimensional coordinates of small molecules can be converted to molecular descriptor strings that encode them uniquely in order to enable small-molecule recognition, despite high variability in atom and molecule nomenclature. From this descriptor a plausible 3D structure can be regenerated using energy minimisation. Alternatively, an ensemble of structures can be generated using a distance-geometry-based algorithm.