This project works best with those 90's rayon tank tops you can easily find at a thrift shop (and maybe even in the back of your closet... shhh, we won't tell!). While it will theoretically work with a knit tank top, rayon or some other thin woven material will fold down smaller and won't stretch if you've got a lot of groceries in your bag. Also, it helps if the necklines on the front and the back of the tank top are similar (versus a tank top with a low cut front and a higher neckline in the back, or a racerback or halter style).
In addition to a refashionable tank, you'll need 5-6 inches of snap tape or ribbon...
Step 1: Givin' waste the cold shoulder
NOTE: If you are really in a super rush to get your grocery on, you can skip this step and Step 2. While it can be a time-saver, it will also leave your bag looking less polished and it won't open as wide as if you take these extra steps. If you do plan to skip steps 1 & 2, simply turn the tank top inside out so that the side seams are in the front and back of the bag, instead of on the sides and don't do any cutting just yet. Then skip on to step 3!