Anaglyph glasses achieve the 3D effect by covering each eye with different chromatically opposite colored filters. while viewing the two different images similarly filtered, resulting in only the one intended image being able to reach the intended eye. Then the eyes and the brain take over producing one three-dimensional image.
Some cardboard framed anaglyph glasses have been produced in themed subjects, for special occasions, or to accompany the sale of 3D content (video & DVDs). See these selections in the category, 3D Themed Glasses