This brilliant t-shirt idea originally came from the workman family blog. I added the green painter's tape edging because I'm a perfectionist it was easier for my kids to judge how much room they had for the actual handprint.
1. Using painter's tape, mask off the sides of the flag
2. Paint in the white area using red acrylic paint
3. Remove painter's tape and make handprint in the centre
4. Ta-da
We used old school uniform t-shirts and a dollar store tube of acrylic paint we had on hand, so this project came together for zero cost and zero fuss. Just the way I like it.