Hi Thomas, There is a Chimera extension that produces an MRC density map from a PDB file. It is part of the Analysis of Intermediate Resolution Structures (AIRS) toolkit that is distributed with the EM single article reconstruction package EMAN1. http://ncmi.bcm.tmc.edu/software/AIRS http://blake.bcm.tmc.edu/eman If you install EMAN and configure Chimera to find the EMAN / Chimera extensions as described here http://ncmi.bcm.tmc.edu/software/AIRS/doc_html then there will be a Chimera menu entry Tools / AIRS / PDB to MRC. It allows you to specify a resolution and number of angstroms per pixel for the map. This is a good bit of work to setup and I plan on including the ability to make a density map from a PDB model directly in Chimera distributions in the future. It will use a Gaussian for each atom. I'll add this to my list of requested Chimera features. http://www.cgl.ucsf.edu/chimera/plans.html Thanks for the suggestion. Tom