Now almost a year later I finally did it. I love how it turned out. I also decided to take on the challenge of making a tutorial out of it in hope that some of you can find a similar tank and do the same.
On to the tutorial! (Note: read all the way through before cutting and sewing).
This is the before picture. She thought it was fun just like this and I had a hard time getting it off of her. When I finally did these are the next steps I took.
First I put one of the tanks on the kid, and measured it to where I wanted it to sit and how tight around I wanted it to be. I marked them with pins. Essentially it was about 2 1/2" in on each side. It will probably be different for your child depending on their size.
Next each side of the tank, and also carefully cut off straps. You will have two pieces. The reason I cut them apart is because with the elastic back it just made it easier to get them cut right.
Make sure to pin your elastic on the back piece in place so you don't have to restring the elastic through.
Take the front piece, and fold it over right sides together and line up the edges.
Find your mark at the top from measuring the child, and cut at a diagonal. Do the same with the back piece of the tank.
Line up the sides, and pin them together. Sew sides with a 1/2 seam allowance.
Once your sides have been sewn it should look something like this.
If you have a serger you can finish it off like this. If not, then you can use a zig zag stitch to help finish it off.
Trim away any extra from the bottom.
Using the second tank top you will cut it into two parts for now. Carefully cut just under the elastic band through both front and back of tank. This will be the ruffle. Set the rest of the tank aside for the sleeves.
Now, you are going to slightly gather the piece you just cut off until it is the same size around as the bottom part of the dress piece.
After it is gathered to your liking you will pin the ruffle piece to the dress piece with right sides together. (This is where I forgot to keep taking pictures)
Finish it off with a serger or a zig zag stitch.
For the sleeves you will take the left over tank and cut the sides. Now you should have just the left over back piece. Mine had an elastic piece where I cut it away from the ruffle piece, as well as an elastic piece at the very top of the back.
Next cut this piece in half horizontally. You should have two long pieces each one having one elastic piece. If there is no elastic, measure from front to back on the child where the sleeves would go, and add 3-4 inches. Make a casing for an elastic and pull your elastic through your casing and sew it into place.
Once you have your elastic sleeves ready you will finish off the raw edges by folding and pressing a 1/4" seem and top stitching it.
Position sleeves about 3" in on each side and pin in place (the measurement or placement of the sleeves will vary depending on the child. Sew them on front and back.
Now, you should have a dress similar to the one I have made.
I apologize now for any confusion. If you have any questions feel free to ask. Next time I really need to remember all of the pictures.
Good luck repurposing.