Haley Pierson-Cox from The Zen of Making and Craft shows to use a block printing to create your own custom printed t-shirt. We love all things kitty at our house, so I squealed when I saw the kitty face print that she made. (Especially since all three of our cats are black cats.) AND her tutorial includes a template for the kitty face. Go to her block printing tutorial and kitty template.
[photo from The Zen of Making]