http://www.pnas.org/site/misc/classics1.shtml

After several trials of model-making, and just as many
errors, Pauling finally hit on the first--and still most
important--structure defined in his protein papers. While
confined to bed with a bad cold, Pauling claims that he
amused himself by drawing chemical structures on pieces of
paper. By twisting the paper to simulate chemical bonds
between segments, Pauling finally grasped the structure of
the alpha helix.