This light-weight vest, or cover-up was fashioned from a flared bottom tank top that was once attached to a blouse. The shoulder seams had to be cut in order to remove it, and I was afraid that creating new shoulder seams would leave the arm holes too small. So in order to work around that, I created a couple of tabs using a similar weight knit fabric from an old dress.
This is one of those things you just have to figure out as you go along...there's not tutorial, or even hard and fast rules for creating it. So, the best I can do here is tell you how I went about it. I did all the stitching by hand, but there's no reason you couldn't use your machine for this. I chose to do hand stitching because the tank was made from a very delicate knit, and because I didn't really know where I was going with this, I didn't want to have to rip out machine stitching.
Before cutting up the center of the tank, I fused a piece of medium-weight interfacing down the length of the tank to create a little stability, and prevent the knit fabric from rolling. I then folded and pressed (twice) before hand stitching.
The top tab is a rectangle that I folded under on each of the long sides, and then at one short end to create a point. I also made smaller rectangle tabs for the underside so that no raw edges are showing. I gathered the tank straps a little bit so they would fit the tabs. I began sewing the tabs by placing right sides together at the straight end of the tab, and the back strap of the tank, and stitched the tab to the tank. I then folded it over, sewed the tab to the front strap just above the v-point. Finally, I placed the smaller rectangular tabs underneath, attached the short ends to the tank, and used a slip stitch to sew the top and bottom tabs together at the sides. The white stitching was done last, and is just decorative.
Before cutting the tabs, and leaves, I fused a medium weight interfacing to the knit. The visible stitching was done with a heavy-weight thread so that it would stand out.