SH2 (SRC Homology 2) domains are a type of protein structure found widely in nature:
http://en.wikipedia.org/wiki/SH2_domain

This SH2 domain is from human p56lck. Model based on the Protein Data Bank entry 1LKK:
http://www.rcsb.org/pdb/explore.do?structureId=1LKK

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

Successfully printed in PLA on a Makerbot Replicator2 using MakerWare 2.2.2.89, standard resolution with 3 shells and 25% infill. Use rafts and supports.