Complex sentence: Alternatively, a piece of paper with a relatively small opening cut into it can be used in a similar manner; correctly positioned between the images and the viewer, it will appear to be a frame around a small three-dimensional image.
Split into simpler sentences: Alternatively, a piece of paper with a relatively small opening cut into it can be used in a similar manner. Correctly positioned between the images and the viewer, it will appear to be a frame around a small three-dimensional image.