Bare with me as I give you a tutorial. Please leave a comment if any part of this tutorial isn't clear, I'm still working on my tute skills!
Here's the picture of the pink top. I used it as a pattern and simply cut out around the top (you can use any tank top, just make sure you cut the neck similiar to the one in to photo below.
I also cut my front and back the same, just to make it easier for me. On the original top the back was higher and the arm holes came in more.
Once you have the front and back cut; sew a small quarter inch inseam around the arm holes. (If you have a serger you can sure around the sides of the top at this time, before doing the inseam).
Next you'll want to measure the neckline for the braid. G's was 17 inches (for a 12month top) around. I cut 3 pieces of coordinating fabric about 1inchx24inches. Make sure you add a few inches to the length of the fabric before you start to braid, you can always cut that off later.
I found the easiest way to start the braid was to tie all 3 pieces together in a knot. Once you are done braiding sew over the ends with a zig zap stitch a few times. (You'll want to go slow so you don't break your needle. Or even swap out your regular needle for a stronger one)
Here are my three pieces. I started braiding and decided to swap out the teal for another purple piece.
Once the braid is done set it aside.
Take your front and back piece and sew them together.
Now take your braid and place it along the neckline of the top and slowly sew the braid on. Don't move too fast or you'll break your needle.
Tada! Your top is done. The neckline was a little small and a bit hard to get into G's extra large head. You may have to end up cutting/sewing a small keyhole in the back, depending on your little one.