I just answered this three days ago. The Alice in Wonderland book is too old and is no longer copyrighted. You may make a Mad Hatter hat. What you cannot duplicate is the two recent movie versions, the cartoon and the new movie EXCEPT some of those characters are exact replicas of the original drawings, like the Cheshire cat smile.
I made an Alice cake with all the characters. It's on my site. There is no doubt that the hat, watch, bottles, cake, etc, are from the book. But not one is from the movie.
You can easily make a hat that everyone will associate with the Mad Hatter. Just don't make it similar, even remotely, to the two movies.
Interesting! I didn't know a copyright would "expire"! How does one find out if a character is "too old"?
In the US, anything published before 1923 has an expired copyright. For all original work starting in 1923 (the year Disney was founded) the term is 95 years from publication, which means that works created in 1923 and after will start becoming public domain in 2018. However, Disney will likely lobby to extend this (as they have done before) to keep Mickey Mouse under copyright protection.
http://en.wikipedia.org/wiki/Copyright_Term_Extension_Act
Alice in Wonderland was published in 1865 so it is in the public domain, meaning that you can use the characters however you wish for personal or commercial use. However you cannot base your characters on Disney's version of Alice, since Disney's interpretation of the characters and artwork is copyrighted and will likely be protected in perpetuity.
http://en.wikipedia.org/wiki/List_of_countries%27_copyright_length
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