Designing a custom t-shirt for your birthday party is simple; we work together to make a design that you're happy with and coordinates with whatever theme you have in mind. If we are also creating invitations and other printed items, then the graphics can match.
Recommendations:
First, choose t-shirts that are 100% cotton. It's recommended to prewash them to account for any shrinkage and then iron the shirt to create a smooth surface before you being adding the graphic.
Iron-on fabric transfer paper is available at most office supply and craft stores. Choose the paper that is appropriate for the shirt you're using. It's available for both light and dark shirts. The dark shirt paper can work on light shirts, but the light shirt paper will not work on dark t-shirts.
To adhere the graphic to a t-shirt, print the design onto iron-on paper. Please note whether the directions specify that you print a mirror image of the graphic. Typically paper designed for light fabrics requires a mirror image print.
Carefully cut out the design and then iron it onto the shirt following the directions that came with the paper.
If you would like to have your t-shirt graphic professionally printed onto a t-shirt please don't hesitate to ask me for a quote. I have worked with a couple of small shops that can do professionally screened t-shirts with custom graphics.