In my experiences, Cafepress will not let you use any copyrighted material. I don't know if they have changed that rule or not, the last time I used it was a year ago.

Examples of Prohibited Content

In accordance with intellectual property laws, CafePress has certain rules regarding the types of merchandise that you can make and sell through its service. For example:

NO UNOFFICIAL MERCHANDISE, such as professional sports teams, videogame or Olympics merchandise.
NO use of names, logos, pictures or other intellectual property of musical groups or musical artists. For example, you cannot make Britney Spears merchandise simply because you run a fan-based Britney Spears website or just because you downloaded her image from an internet website. You also cannot modify the name or other intellectual property of a musical group and avoid infringement, (e.g., using Metalika instead of Metallica).
NO use of names, logos, pictures, or other intellectual property of sports teams, colleges/universities, clubs, or organizations such as the Los Angeles Lakers, Harvard University, or The Boy Scouts. Modifications may not avoid infringement.
NO photos, logos, caricatures, or other artwork depicting celebrities, such as Michael Jackson or Madonna, or other third parties. Just because you take a photograph of a celebrity does not give you the right to use that photograph on merchandise, even if you digitally manipulate the photograph. Political figures are permissible because there is an exception to the general rule for political figures.
NO use of trademarks, names, or logos of companies. For example, you cannot use the name of a company such as Nike or company logo such as the Nike "swoosh" trademark.
NO pictures or photographs of products (such as toys). Even if you own a product, trademark laws may still prohibit you from selling merchandise that features pictures of it. For example, you cannot take a picture of your Barbie and sell Barbie merchandise with that picture.