All of the work is in the placement of the camera, light and the objects. Define an object, such as a sphere or a box of two units in size located at the origin and apply a texture to it. Place a camera about 15 units away along the -Z axis, pointing at the origin. The tiled plane in the background is just behind the eyes. The final, and most important secret for creating these images is the placement of the lights.
Shadows give visual cues regarding the depth and placement of objects.
Shadows in this type of cross-eyed stereogram give conflicting information to your eye. To eliminate shadows, just place the single light source at the precise position of the camera. For a real strange effect - view this image using the divergent viewing technique common to RDS images. The 3D effect will be reversed, with the green plane in the foreground and the concave eye shells pointing away from you. The IRIS and the Eyeball Creating the iris of this eyeball was especially interesting.