Syndiant creates a 3D pico-projector by taping together 2 projectors...

Syndiant wanted to show a 3D demo with their pico projectors, and did it in a cool way. The took two prototype pico projectors, put polarizing films in each, and taped them together. The images were precisely aligned - and you get a 3D image (you need polarized glasses for this).

Nice trick. Obviously you need to position this careful to reproduce...

via SID 2010