I started with a size large tank top. I figured that starting with a larger size would give me a little extra scrap in the end should I need to mend anything later. This one still had the original tag from the store it came from, so it was brand new! Thankfully for "sales", I got this one for a couple bucks.
What I did was cut the front and the back apart and worked with one side at a time. I cut the bodice to the width I need for my little girls' 2T frame. I did my best to keep the pleated detail intact because it's really cute. I cut the spaghetti straps off to use them on the finished dress. I also cut off the two that went across the back to use them later too. With the extra I had left over from cutting the front bodice out, I pressed some bias tape and sewed up along the two new arm holes. I then replaced the straps on the top of the front bodice.
For the back of the dress, I was lucky that this shirt had a 1/4" elastic simply cased in along the entire top part. I made sure to pin the elastic in place before cutting and then pulling the elastic out just a bit to keep the bulk of the fabric for the dress. I hope that just made sense. In other words. I kept the back of the shirt intact and only pulled the elastic in to have more scrunch to it before sewing it place.
What's left for tomorrow will be the hem job on the bottom. It's a little too long right now but i'm going to be keeping a lot of it and sewing up a large portion so that I can let it out as my little one grows taller.
Thanks for looking! If you have any questions, just send me a comment :)