For this project you will need about a yard of fabric (less if you are doing a smaller size. This one is size 6), two yards or more (depending on the size of your garment) of double fold bias tape or 7/8 inch ribbon, a tiny bit of small elastic, a button (doesn't need to match). Button and elastic are optional.
1: Find a tshirt that fits well, fold it in half and lay it on top of a paper that is folded in half
2: Cut around that and unfold. Looky there, a pattern! This one is for the back.
3:Fold the pattern down from the neckline of one shoulder, down to a couple of inches below the armpit
Boom. Front pattern piece.
4: Cut one of the back (it helps if you fold the fabric and pattern back in half and cut on the fold.) and two of the front. Trim off an inch or so of the front flap so that there is room for the ties.
5: Pin ties into seam. Lay down the back piece and lay the tie down a tad below the armpit in the same place the front ends. Lay the front pieces down, right sides facing the back. the ribbon should be sandwiched between the front and back. Pin all seams.
6: Sew a rolled hem on the front flaps.
7: Sew the shoulders
8: Sew the side seams. Open the armpit when you get to it so that the seam will keep going straight. Take your time here to make sure you are catching both layers. When you get to the ribbon/bias tape that is stuck between the font and back with a little bit sticking out, reverse stitch to make it more sturdy.
9: Roll hem the sleeves and bottom and turn right side out.
10: Fold your bias tape over the end of the front flap, heading up onto the collar, leaving 12 inches hanging off the end. Make sure the tail is pointing to the side that the tie is sewn onto. Sew around the whole collar.
11: When you get to the end of the collar to the other flap, you have two choices:
A) If you choose to have it tie on the inside: Leave the second tail, and adhere a second 12 inch tie on the inside seam allowance of the corresponding side. This is what I did, but I wish I had done B.
B) If you choose to use the button and elastic, fold under the end of your tape, tuck it under and sew it down. Sew a button onto the corner of the flap on top of the tape. Sew a loop of elastic to the seam allowance on the corresponding side. Tack it down really well. A snap might work okay, too.
Other notes: If you want to put a sleeve on separate from the body, I found this tutorial very helpful. I did sleeves for the second one I made (the dot one) because I was working with scraps.
This technique works really well for kids because they are straight up and down. I can't vouch for adult sizes because there are more curves and the drape will be different, but you can try it. You will probably have enough fabric left over to use for at least the cuffs for a matching pair of trousers. I'd love to see how these turn out for you!