I haven’t had a chance to play The Rivals for Catan, but I just noticed that Mayfair has a custom card creator for the game. Here’s how they describe it:
Here you have the possibility to create your very own playing card within minutes. The “Harald” card serves as a template. Just insert a picture, choose a name, and create a short text for your very own hero card. After that, all you have to do is save your work as a JPG or PDF file, print it, and glue it to the original “Harald” card.