Collagen

"About one quarter of all of the protein in your body is collagen. Collagen is a major structural protein, forming molecular cables that strengthen the tendons and vast, resilient sheets that support the skin and internal organs."
--http://www.rcsb.org/pdb/101/motm.do?momID=4

Each STL file contains one of the three strands that makes collagen. Model based on the Protein Data Bank entry 1CAG:
--http://www.pdb.org/pdb/explore/explore.do?pdbId=1cag

Model created using VMD:
http://www.ks.uiuc.edu/Research/vmd/