Red and cyan are said to be complementary because a red filter will not let through cyan light and a cyan filter will not allow through any red light. The red and cyan pictures are overlapped. 3-D is to project each image on a screen with crossed polarizers and then view the image with similarly crossed polarized glasses. This cannot be used on a normal computer screen. With computers one can blink between two images on the screen and then wear special glasses that alternately shutter one eye then the other in syncronization with the blinking images.
M aking anaglyph glasses is pretty simple.
As discussed above, all you need are two colored filters that are complementary colors. Typical anaglyphs have you put the red filter on the left eye and the cyan filter on the right eye. Cut out cardboard eyeglass frames and tape the filters over the eye holes. If you need a template for the glasses, click here .