Things You'll Need
Instructions
Cut one T-shirt off at the waist, or at the point where the shirt hits your belly button.
Cut the second T-shirt just below the arms, so that you are left with the bottom portion of the T-shirt.
Sew the bottom of the first T-shirt to the top of the second T-shirt with needle and thread. Make the seam even as you go around. You can do this by hand or with a sewing machine.
Measure the 6-inch strip of fabric around the circumference of the dress's hem. Cut the fabric so that it fits all the way around the hem. You can sew the fabric onto the hem, or use a hot glue gun to attach it to the T-shirt sundress. The fabric acts as the dress's bottom trim.
Leave the sleeves of the top T-shirt intact, or cut them off for a sleeveless sundress. Either way, decorate the trim of the sleeves or the tank with more of your 6-inch fabric.
Wear a belt around the waistline where the two T-shirt were sewn together. Not only does the belt act as a stylish accessory, it also hides the seam. Disguising the seam gives the appearance that the sundress is made from one piece of fabric.