I followed a method I found online, but stupidly didn't bookmark the site, and now I can't figure out where it is. It involves pinning the existing T to a flat surface and tracing out. Sounds simple but you have to use pin marks to delineate the seams on the parts of the shirt you cant actually draw because those seams are enclosed within the shirt (i.e. shoulders and neck line - remember T shirt necklines and sleeve openings are ribbed).
Then you have to take that 1 piece sloper and cut out the individual pieces (front, back, sleeves) and add seam allowances. Then you have to draft your ribbing separately. To make 1 inch ribbing for the neckline, I cut 2.5 inches (enough for fold over and seam allowances) and made the piece 2/3 the length of the open neckline. I followed the same ratio with the sleeve ribbing.
The prep has taken a few hours, but the sewing will begin apace. Wish me luck. I have enough fabric for 2 Ts...

