Here is an interesting application of 3d printing: using it to print organic structures of cells and different organic molecules for research and education. If you can touch it and manipulate it, you can understand it.
Here is an image of printed Beta Cell model. Sometimes parts are individually painted and glued or they use magnetic connectors as links in molecules.
Cyanovirin in spheres with ball n stick ligands. 20 Million X.
Those models were done by Scripps Physical Model Service.
Check their cool gallery at:
Another project aims directly at education institutions
Here is video demonstration of 3d printed self assembling virus (89.95$):