Take a shapeless t-shirt, sew four seams and end up with a fitted top.
Free t-shirts are almost never girl shaped. Here is one technique for making your freebie wearable. Darts in the front and back contour the shirt to fit your curves.
Some basic parameters: I used a size 11 regular point needle and a lightning seam for stretch fabric. I did not use a ball-point needle for knits and I did not have any problems. As far as stitch length and width, I followed the guidelines for lightning stitch in the manual that came with my machine: medium length and medium width. Your machine may vary.
We’ll start with a basic t-shirt from Maker Faire.
Put the shirt on and pin a safety pin just under the center of each breast. Also pin at the part of your hip bone that juts forward, and just under your bra line. This should give you a line of three pins on each side at the high points and the low points.
Turn the shirt inside out and pick one of the seams to start with. For that seam, replace the safety pins with straight pins.
Fold along the line marked by the pins. Depending on how curvy you are, you may need to adjust how much you take in. Start with a conservative guess, since you can always take more. On the front I used about three-quarters of an inch at the deepest point. Mark that point and then draw a line from the maximum to the end points.
When you start to sew the seam, you’ll want to start the needle right on the edge of the fold. Bring the needle down to just above the fabric so you can adjust the position of the fabric. Sew along the line to a bit before the deepest point. Gradually turn the fabric to form a curve to head back along the line toward the fold again.
The front seam needs to be more gradual at the top or it will be a bit pointy on the breast. My first try was not quite gradual enough, so I started a new seam slightly back from the end to make a more gradual curve.
That’s it, we’re all curvy now! And the now shirt matches the recently modified Maker Faire bag. Well, it would if I added a pocket protector!