A brass Kendrew model of the Staphylococcal nuclease crystal structure, decorated along the polypeptide backbone (green) and inhibitor (red) with tygon tubing containing fluorescent dye.  a) room light, b) room + UV light, c) UV light, d) a "worm" drawing made by Jane Richardson from these photos.  Part c is a precursor to molecular graphics, and part d is a precursor to ribbon diagrams.
<a href="//commons.wikimedia.org/wiki/User:Dcrjsr" title="User:Dcrjsr">Dcrjsr</a>
CC BY 3.0
<span class="int-own-work" lang="en">Own work</span>