1. Gather your supplies: A pillowcase (or fabric approximately the same size), scissors, measuring tape, strait pins, marking pen (preferably disappearing), sewing machine (although could be done by hand) and thread, iron, arm hole template, and ribbon.
2. Measure for desired length. You can either measure the intended wearer, or use a dress that fits well and measure the length of that dress. It is best to measure from the bottom of the arm hole down to the bottom hem. On my dress it was around 14".
3. I measured 14" up on the pillowcase (from the bottom/open end up) and put a pin in. I then printed and cut the arm hole template (I like the template for size 2t-3t, but for larger sizes I would add 1 1/2" to the top and side (the little tab on the side) of the pattern or, just use an existing dress, trace the arm hole and add 1 1/2" to the top for the casing). I lined the bottom edge of the arm hole template up with the pin marking the bottom of my arm hole.
4. Cut off the top. I lined my ruler up with the top of the template and used my rotary cutter to cut the top off. You could do this with scissors too, just use diapering ink pen to mark the cut line and cut with scissors.
6. Make the hem for the arm holes. Do this by turning the raw edge in 1/4" or so twice. I start in the middle. Fold it in, then in again, pin in place. Keep moving up all the sides.
this pattern. I sized it down a little, and cut the legs shorter for shorts. I used my serger to add a rolled hem edge to the bottom of the legs and then used a shirring technique (elastic thread in the bobbin) to make the gather at the bottom of the legs. I made this outfit for my 20 month old niece. Just don't tell my hubby that I used my little boy as a model. :)
Just saw this SUPER CUTE pattern: http://www.themotherhuddle.com/tutorial-fat-quarter-pillow-case-dress/
Happy Crafting everyone!