Made these shirts the other day using the same freezer paper stencil idea. If you want to make some, google search freezer paper stencils! All you do is cut out an image in freezer paper, iron it on, paint with tulip paint, let it dry, and enjoy!
I have a hard time finding his size at the store with the cool shirts, so this solves all those problems! Also, wouldn't matching shirts for the whole family be fun?