How can I create custom designs on t-shirts using freezer paper?

To create custom designs on t-shirts using freezer paper, you can first draw or print your design on the non-shiny side of the freezer paper. Then, carefully cut out the design using a craft knife to create a stencil. Place the stencil shiny side down on the t-shirt and iron it to adhere it. Finally, use fabric paint to fill in the stencil, let it dry, and then carefully peel off the freezer paper to reveal your custom design.