How to Turn Your Smartphone Into a Hologram Projector

Finally, a use for all those old CD jewel cases: turning your smartphone into a tiny hologram projector. By making a sort of half-prism with cut out pieces of a jewel case, your smartphone will reflect images from special "hologram" videos, making the projection appear 3D. Some YouTubers are less than impressed, dismissing the image as "just a reflection," but the effect is still definitely cool even if it's not technically a real hologram. (Other commenters are predictably requesting hologram p...