I thought that the drawstring could be a choking hazard so i replaced it with elastic. The straps are fixed.
All you need is a piece of fabric - choose the length you'd like the dress to be - get the width by measuring the chest then add 6". You need two pieces like this.
Sew up the side and leave about 4-6" open which will be the armholes. Hem these open sides.
Turn down the top and make a casing for the elastic.
Put in elastic that is about 4" long.
Add ribbons to the ends. Sew over the elastic and where the ribbon joins.
Hem the bottom
I added the ribbon as embellishment and to be continuous with the straps.
This dress was made using different strips of fabric sewn vertically.
I made a couple more:
I used different fabrics to create a unique piece. I dont use a pattern so each one is always different and unique. You can add different embellishments to make each one different.
This one is reversible - patterned on one side and plain on the other