From the Family Fun website, Super Star Shirts.
My boys, neices and nephew made these the night before the Fourth at my mother-in-law’s home. Okay, I made the my baby’s. The girls (11 and 8) LOVED doing them, as did my oldest (6). My middle child (3), as usual, wanted no help whatsoever, and painted his star all on his own (he kept flicking his hand at me while saying “shew, shew”. He’s part old lady, apparently). He mixed the red and blue in a molted sort of way, and it ended up being my favorite! He did allow me to put some silver stripes on after the star dried (he wanted no part of the splattering) and I’m pretty much in love with how his shirt turned out.
We didn’t use fabric paints, just regular ol’ acrylics, and it worked just fine. I’ve even washed them twice since (to try to get the various snow cone, watermelon, general Fourth of July stains out) and they’ve barely faded. For the star stencils, I just printed out some free star clipart off the internet and we traced those onto the freezer paper.
I think we might try a similar activity for our Halloween shirts this year, the whole make-your-own stencil thing was so much fun.