blmol defines a molecule object that can be used to import molecular geometries (from a PDB file) into Blender. It can be used to generate space filling, bond-only, and ball-and-stick models. The script includes definitions for simple default materials that can be used. These should be easily customized.
Simply copy to Blender's scripts folder.
Basic usage is to switch to the Scripting screen layout, then import blmol. Create a molecule object with m = blmol.Molecule(), then load the geometry with m.read_pdb('path/to/file.pdb'). A space filling model can be generated with m.draw_atoms(). Many options can be changed as documented within the comments (more details to come here).