Things You'll Need
Sewing tape measure
Transform a flirty, sleeveless summer dress into a sexy wintertime fashion essential by adding off-the-shoulder sleeves for some extra warmth. Use the same fabric as the rest of the dress for sleeves that blend in, or let them stand out with a different color or texture fabric. You can make form-fitting long sleeves to keep the dress as sexy as you like, or add billowing bell sleeves to the dress for an elegant and feminine touch.
Take some measurements for the sleeves. Measure the circumference of your arm, just below your underarm. Add 1/2 inch to this measurement. Measure down the length you would like the sleeve and add 1 inch. Measure the circumference of your arm here and add 1 inch. For a bell sleeve, multiply the upper arm measurement by 2 for the lower circumference.
Draw the sleeve shape on your fabric with tailor's chalk, according to the measurements you obtained in the above step. Cut out the sleeve shape and use it to make a second sleeve. Alternatively, you can add just one sleeve to the dress.
Fold the sleeve (or sleeves) in half lengthwise with the good side of the fabric facing inward. Sew a running stitch down the length of the sleeve.
Fold over 1/2 inch of fabric along the top and bottom of the sleeve and sew a running stitch. Sew the top of the sleeve with elastic thread. Tug on the elastic thread slightly to gather the top about 1/2 inch. This will make the sleeve fit snugly around your upper arm.
Turn the sleeve (or sleeves) right side out. Hold the sleeve's seam against the side seam at the top of the dress.
Attach the sleeve to the dress by pinning the sleeve to the underarm of the dress. Pin about 3/4 inch of the sleeve on each side of the side seam. Sew it in place with a running stitch.