I wanted a T-shirt dress, but I don't know how to use a sewing machine and sewing by hand often takes forever. After a bit of technique searches and experimenting this is what I came up with.
Cutting approximately 1 cm away from the seam, remove the neckline and sleeves from the shirt.
Cut open both sides of the t-shirt. Fold the t-shirt in half lengthwise, to begin cutting notches.
Cut "V" shaped notches along the sides of the shirt. Unfold the shirt and tie the sides together.
Uh, WEAR IT!!!