I used UCSF Chimera: https://www.cgl.ucsf.edu/chimera/

To generate geometry from this GFP molecule: http://www.rcsb.org/pdb/explore.do?structureId=1GFL

As a demo in response to this thread: http://3dprint.nih.gov/engage/forum/printing-ribbon-structures

and this thread, explaining how I made the ribbons thicker: http://3dprint.nih.gov/comment/36#comment-36

Then I oriented the geometry for easy splicing in two peices and then cut in two.  I should have also scaled it up in size, as I had to increase the size x20 in Repetier Host before printing.

Next step is to embed green led lights for a display case!  :)