Make a baby dress out of a t-shirt (or two): Cut off the bottom, then use a currently-fitting dress or shirt as a pattern to cut the sides and arms. Sew up the sides + arms. Gather the bottom of this or another shirt and attach for a skirt. Thread collar with ribbon to make it adjustable. A 3T t-shirt will make a long-sleeved baby dress, an adult medium t-shirt will make a little girl's long-sleeved dress.