Here's a quick little craft to show your patriotic spirit! You'll need a plain t-shirt and fabric paint.
I probably should have washed and dried this shirt before we did this craft, but alas, I am lazy and did not (Please pardon my wrinkles). It's really quite a simple process that doesn't need much explaination.
Simply use your childs handprint for the blue section of the flag, and then have them paint the stripes in red. I mixed in a bit of glitter paint, because as I have previously stated, I am a sucker for glitter. Let dry for at least 24 hours before wearing. You may want to iron the image (use parchment paper as a buffer)