[cctbxbb] e density from atomic model?

Crystallography pros, Field-outsider asking for advice here. Is there a standard way to estimate the electron density on a grid from an atomic model (e.g. PDB coordinates of atoms)? One thing that occurred to me was to simply FT the Cromer-Mann atom-centered Gaussians commonly used to model atomic form factors. Perhaps there is a more standard way, though? And possible code to mooch...? Thanks much! TJ