3D Printing Sites/blogs:
Make Magazine's Posts on 3D Printing
https://thre3d.com/what-is-3d-printing
http://www.3ders.org/
3D printing in the News
High school students solve the ketchup problem with 3D printing
TinkerCAD
123D Design
A more technical explanation of 3D printing:
Find out even more at Thre3D.com
"Magic Arms"
Project Daniel