After the failure of the Virtual Boy, few companies were willing to put much development or marketing muscle into stereoscopic console gaming. In 2006, however, an interesting, inexpensive alternative emerged from Konami: the Tobidacid Solid Eye. This simple cardboard peripheral for the Sony PlayStation Portable handheld shipped with every copy of Metal Gear Acid 2; users folded it together and placed it over their PSP screen. Konami designed the game to output two images, one for each eye on each half of the PSP display. The Solid Eye directed each eye to the correct image, creating a 3D effect.
Photos: Konami, PSP Gadgetz