3. Using chalk, re-draw the sleeve line into a curve that reflects the shoulder width that you’d like for your tank top. For instance, in the photo above, I cut my daughter’s shirt with a big sleeve opening and a wide shoulder, more of a sleeveless T-shirt than a tank top, to mimic the cut of her softball uniform shirt. However, if I’d cut a smaller sleeve opening with a narrower shoulder, it would have looked like a conventional tank top.
4. Cut out the tank top along the chalk lines. Note that although you will not be hemming or otherwise finishing the bottom hem or the sleeves of your tank top, you’ve still cut it with some seam allowance; this is because the jersey knit fabric will not fray, but will naturally roll under a bit. The extra fabric that you’re allowing it will allow it to roll under naturally and still maintain exactly the length and width that you designed.
5. Flip the shirt inside out and re-align and pin the side seams, using an iron if necessary to keep the cut edges of the fabric laying flat.
6. Using a stitch that’s good for jersey knit, sew both side seams, leaving the sleeves and bottom hem unsewn.
The tank top is now ready to wear as-is, although you could also bind the sleeves and bottom hem with jersey knit bias tape, or add lace, ruffles, or any other upcycled embellishments to the garment.