Step 1: Use the Favorite Tank Top to Create a Pattern
First layout your tank top on the newspaper, lining up the edge of the newspaper with the center front or back of the tank top. Trace around the tank (figure 1). Double check that the measurements are at least in the correct ballpark by measuring the unstretched bust, waist, and hem circumferences of the tank top and matching those to the patterns measurements. (This is where I went wrong the first time around, and trust me, not having to take everything apart is awesome, so measure twice and cut once!) Use the curved rulers to smooth out the curved lines of the garment - in this case all seamlines have a slight curve except for the shoulder seams and then cut out the pattern pieces (figure 2). If you plan to add a shelf bra, copy the original front and back patterns to a new piece of newspaper and then cut off the torso to the correct length to go over your bust. Make sure to add an extra 1" to the length for the elastic casing!
Because I knew I wanted to have a contrast material, I drew lines on the front and back pattern where I wanted seamlines, cut them apart and then added seam allowances (generally I add 5/8"). Since we are finishing the neckline and armholes with binding material, do not add seam allowances there. Otherwise, add seam allowances and a hem allowance.
Step 2: Cut Out the T-shirt
Cut the remaining pieces out using the secondary fabric, including some lengths of 1.75" binding. For the binding, if you are using a stretch material, you can cut it on the lengthwise or crosswise grain - I recommend the less stretchy grain, but either will work. If, for some reason, you are using a non-stretch material, cut it out on the bias or else you'll have problems later on.
Step 3: Sew the Tank Top!
Next create the interior bra, finishing through creating the elastic casing - just double over the hem area, stitch down and then pull the elastic through.
With wrong sides together, and the bra section inside the shirt section, pin the two pieces together. Now comes the binding finish - with right sides together, place the bias binding along the curves of the neck and armholes. stitch down with approx 3/8" seam allowance. Turn the binding towards the seam and press. Next tuck the binding up and under on the wrong side of the garment, leaving enough length so that the fold covers the seamline there. Pin and then topstitch the binding in place. I again doubled the topstitching. For a more visual reference, this woman explains this process here: http://thehabygoddess.blogspot.com/2012/08/tutorial-how-to-sew-on-bias-binding.html much better than I could!
And with that, you're done creating the shirt! Only thing left to do is wear it!
Step 4: Wear Your New Tank Top!
(more pictures here, all courtesy of Stephanie Rubesh)