DIY: Bell Sleeve Turtleneck

Below are the dimensions I used, written steps, and some notes I made along the way for things that need extra attention.

1 collar, 20 cm x 35 cm
2 lantern sleeves, 28 cm x 60 cm each

1. Sew the front to the back, right sides together along the shoulders with a straight stitch
2. Pin and sew the sleeves to the armholes, right sides together with a zigzag stitch
3. Fold the collar in half right sides together, sew the two farthest edges together with a straight stitch
4. Fold the collar to hide away the raw edges, folding the whole tube in half all the way around
5. Pull the sweater neck hole into the collar, right sides touching, and pin together along the back middle, front middle, two sides, and continue to pin along halfway points until the pins are approx. 2 cm apart
6. Sew the collar to the neck hole along the raw edge with a zigzag stitch
7. Pin the armpit front and back, right sides together and sew with a zigzag stitch (stop about 20 cm from the end of the sleeve, and 10 cm from the bottom of the sweater)
8. Try on the sweater and mark with a pin where your elbow rests naturally
9. Fold the lanterns in half right sides together, sew the two farthest edges together with a straight stitch
10. Pull the lanterns over the sweater sleeve, right sides together, and pin the lantern's seam to the sleeve seem at the marked elbow point
11. Pin the side opposite to the lantern seam and opposite to the sleeve seam together at the same elbow height
12. Continue pinning the lantern to the sleeve, finding mid-points until the pins are approx. 2 cm apart
13. With the excess lantern fabric between the pins, alternate between brushing them left and folding right, and brushing them right and folding left, secure all of these with pins
14. Sew all the way around each lantern to secure it to the sleeve along the box-pleat folds
15. Hem the raw edge of the sleeve, lantern, and bottom by folding in 1 cm and using a thin zigzag stitch

- knit fabrics don't need a lot of seam allowance, so 1 cm should be the maximum
- make sure the collar piece is narrower than the neck hole, but fits comfortably around the neck and can stretch over the head
- add the collar before trying on the sweater to prevent ripping the fabric

Comment and let me know if there's anything else you need!