Abstract: Color-changing inks are used in conjunction with printed material, with defined fields to create unique designs and/or works of art. In the preferred embodiment, pre-printed pages or books are used with fields of invisible inks that are activated with different pens to produce a unique final product. In alternative embodiments, stickers, paints, flocking, foil stamping, thermography, embossing and rubber stamps may be used. In specific embodiments, depictions of cartoon characters or other humans or animals are intermingled with more geometric fields, often with instructions or text explaining to a user what actions should be taken for a desired effect or outcome. Patterns of “invisible inks” having desired properties are pre-printed onto materials according to the invention, such that, through the use of different activator pens, different colors are produced in the various fields, thereby rendering a unique product in each case.