Please let me preface this tutorial by saying I am NOT a seamstress. I am a self-taught sewing hobbyist and may have some "unconventional" ways of doing things.
What you'll need:
about 1 yard each of two contrasting fabrics
about 1/4 yard of fusible interfacing
1. Print out the pattern (I'm going to upload it for downloading soon) (this one is about a size 3T), tape it together and cut it out as shown here (or make your own).
2. Cut out fabric and interfacing.
Line up the side labeled "fold" on the fold of your fabric. You will need a front and a back piece for each fabric. Use the top section of the front and back pattern to cut out 1 top and 1 back piece of interfacing.
3. Iron the fusible interfacing pieces to the WRONG side of ONE of your dress fronts and backs.
4. With RIGHT sides together, sew a 5/8" seam at sides for each dress.
5. Press side-seams flat on inside of dress then press 1/4" hem under at bottom of each dress.
6. Put RIGHT sides of dresses together. Do this by turning ONE dress right side out and sliding it inside the other.
Align the side seams, straps, fronts and backs of the dresses and pin in place.
Stitch neck, shoulders, and arm hole edges together. Trim the seam and notch around the curves.
7. Turn dress so the WRONG sides are facing each other and press. Align side seams and stitch in the ditch along both side seams to hold dresses in place.
8. Align both hems and sew along the edge to close the hem.
9. sew button holes in position on FRONT shoulders and sew buttons on each side in position on BACK shoulders.