Thanks Takanori - that's just what I needed - works brilliantly!  : )
I did find that my cgo_line_width setting (1.0) was causing the resultant cgo 'mesh' to appear / draw / raytrace differently to the isomesh counterpart; but I seemed to solve this by setting to -1.  The only slight problem I still have is that 'matrix_copy' does not seem to apply a molecule object's matrix to CGOs (or, for that matter to isomeshes).  This isn't a huge issue, since for most of what I'm doing I can apply a matrix_copy to a map object, then generate the isomesh, then generate the cgo...  It does mean, however, that I am unable to store protein + a number of cgo meshes, with the ability to align the whole ensemble onto another system (which ideally is what I would like to do).  I guess I should maybe follow-up with a more specific post on this point.
Kind regards

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