Nintendo 3DS?

[YinYin]

It's, and this is proven, NOT possible to create real 3D effects without the user wearing something (f.e. glasses), since the 3D effects bases on both eyes seeing different things... which is impossible on a single screen.

you do realize that one screen that polarizes at adjustable angles could display pictures that you can only see from a certain angle (thus producing images that only one of your eyes can see and then switching to the other)

your distance to the screen and how far your eyes are apart is crucial - thats why its adjustable, theres a slider on the 3ds for this