Here are some of my favorite books and articles about 3D Printing:

Books

3D Printing will Rock the World by John Hornick

Fabricated by Hod Lipson & Melba Kurman

Makers by Chris Anderson

Articles

3D Opportunity by Mark Cotteleer & Jim Joyce

3-D Printing will Change the World by Richard D'Aveni

Are you Ready for 3D Printing? by Daniel Cohen, Kathy George & Colin Shaw

The Printed World by The Economist

What Lies Ahead for 3-D Printing? by Elizabeth Royte