3-D Without Glasses
3-D without glasses is for "eye-wallers" and "eye-crossers."
Eye-wallers are people who can easily relax their eyes into 'the distance' and see the 3-D Magic Eye stereograms in the comics pages.
Eye-crossers are people with good control over crossing their eyes (a skill typically learned in grade school).
Either works fine, just so the L & R pictures are on the correct sides.