The sweater itself was really easy to make, I used mostly straight lines, see the illustration and instructions below for details on how you can make your own. I bet you could do something similar with a thrifted or hand-me-down sweater.
You'll want to make your pattern first. Draw up your pattern on butcher paper, cardboard, newsprint, whatever. I typically have my model and a well-fitting shirt on hand to get a good fit. Measure your model's chest, divide by two and add 1 inch (based on a 1/2 inch seam allowance). Draw the line out on your paper. Measure down to the waist. Do the same thing for the waist measurement. Measure the length of your sweater and use a shirt as your guide for the neckline. Instead of doing inset sleeves, I just draw straight lines from shoulder to pit. This will make it so easy to sew. Since you'll be sewing with a stretchy material, the fit doesn't have to be super perfect.
Measure your arm width at pit and wrist and draw up your simple pattern using straight lines. You can refer back to your shirt as a reference, if needed.
Cut on grain, and match up your grain! Now sew!
- Pin front and back right sides together. Sew shoulder seams and press open.
- Pin body and sleeve right sides together. Sew pit seams and press open.
- pin sides (and sleeve) right sides together. Sew side seams and press open.
- Hem sleeves by folding under 1/2 inch and sewing or attach ribbing.
- Hem sweater bottom by folding under 1/2 inch and sewing or attach ribbing.
- Cut ribbing 3 inches wide and as long as your opening (I cut it really long). Pin right sides together along neckline, stretching ribbing as you pin. Sew and press open, with the seam allowance facing down.
- straight stitch with a short stitch length (I used 2.5)
- straight stitch with a double needle and wooly nylon in your bobbin
- a walking foot to keep both layers feeding uniformly
- sew all your seams with a serger