There is a technique called the Abstract Mickey Mouse design that I've used for family t shirts over the years. Get some plain white t shirts, either 50/50 or 100% cotton. Throw them through the washer and dryer. Cut a large piece of cardboard for each shirt, and use it to separate the layers, and lie flat. Use some bowls, and using either a washable felt pen, or some of the kids chalk, draw a large circle and 2 smaller ones to make a mickey mouse head. Get some washable glue, and starting at the bottom use the glue to make a spiral design on the big circle. Then do the same for the ears. Let this dry for at least a day, as it needs to be dry to start the next step. While the glue is drying go to a craft store, and pickup some Tulip fabric spray dye's in the pump bottles. You will need 2 co-ordinating colours. First spray the middle with the first colour in the middle, then spray the second colour around the outside of the first, making sure that the colours overlap a little. Have fun, and don't worry if they are not perfect. Let them dry for a couple of days, then remove the cardboard from the t shirts. You will have a lot of paper stuck to the t shirts, but remove it the best you can and throw all the shirt into the wash with detergent, and a 1/4 cup of vinegar to set the fabric paint. Turn inside out after washing, and rewash again to get out the remainder of the glue. Hope that you have fun no matter what kinds of shirts that you design.