Choose a T-shirt for the top of the dress; cut off bottom 2 inches below the armpit.
Cut 3-inch-wide horizontal strips from 5 different T-shirts. (Tip: Cut strips, then trim off side seams to make two 2 strips of each T-shirt -- one for front, one for back of dress.) Cut one strip from the bottom hem of a T-shirt to make the bottom of the dress.
Optional: Embellish the strips with stamps and fabric paint, or draw and write on the strips with fabric markers.
Place one strip on top of another, wrong sides facing, and sew together strips with a 1/4-inch seam allowance; repeat until all strips are sewn for the front and back. (The seam will be exposed.)
To cut the A-line shape of the dress, layer and center the strip panels below the dress top. Mark each side of top of strip panel, 1/4 inch out from sides of shirt. Measure straight down to hem and mark bottom strip on left and right 1.5 inches out from each point.
Making sure dress bottom pieces are centered and matched, cut each side from top to bottom point.
Sew the front and back together with side seams, with right sides facing. Start sewing at the bottom of the skirt to make sure the sides of the hem line up; take time to ensure that the exposed seams are laying correctly and matching up as you sew.
Invert the dress top inside the skirt to sew the two together. (The seam will be exposed, matching all the other seams.)
6 different worn T-shirts
Stamps and fabric paint, or fabric markers (optional)