7 Bladed Beta Propeller

"In structural biology, a beta-propeller is a type of all-beta protein architecture characterized by 4 to 8 blade-shaped beta sheets arranged toroidally around a central axis."
http://en.wikipedia.org/wiki/Beta-propeller

Model of based on the Protein Data Bank entry 1YFQ:
http://www.rcsb.org/pdb/explore/explore.do?structureId=1yfq
(Yeast Bub3 mitotic checkpoint protein.)

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