This 1930s floor-length evening gown exudes elegance. The star-studded midnight crepe fabric hugs the body starting at the fitted empire midriff, then flares at the bias-cut skirt’s hem. Sprinkled with light-catching silver crystals, the bodice offers extra glitter at the neck and waist with large, faceted azure stones. The real star of this show is the arm treatment. As an alternative to sleeves, a shaped band encircles the armscye in a silhouette-changing detail that defines the waistline and flatters the arm. See more about this shaped band from Threads #164 below.

Adjust the bodice pattern

Start with any sleeveless pattern. If the front pattern has a side-seam bust dart, rotate it to the front hem. Trace a copy of the front and back pattern pieces. Draw all changes on these patterns, and then trace copies of the smaller pieces that overlap.

1. On the front pattern, draw a new armscye from the shoulder seam edge to the side seam, ending 2 or 3 inches above the waist. Follow the original armscye for the top half, and straighten the curve as you extend its length, as shown. Add seam allowances to the new line. Repeat for the back armscye.

2. Make the new facings. On the front and back patterns, draw a line from the shoulder to the side seam 2-1⁄2 inches from the armhole cutting line. Trace the line and the rest of the armscye and seam allowances.

3. Draft an underarm insert to keep the dress modest. Align the original armscye pattern’s side seamlines. Draw a rectangle to include about half of the original lower armscye, and extend it below the waist. Trace the lower armscye and seam allowances.

4. Make the armscye band pattern. On the new armscye, measure from A to B and from C to D and add the two lengths to determine the length of the armscye band. Add 3-1⁄4 inches, and draw a straight line that length. Fold the line in half to determine the center and draw a perpendicular line 3-5⁄8 inches long. From this line, draw a curved line to the ends of the straight line. This is the band pattern and includes the seam allowance.

Sew the armscye band

Cut, interface, and fold two armscye bands with the right sides out. Assemble the garment as usual, leaving the armscye unfinished. Interface the facing pieces and clean-finish their outside edges.

1. Sew the facing seams. With right sides together, join the front and back facings at the shoulder seam. Repeat for the side seams.

2. Start pinning the band at the point where the side seams meet. Center the band’s raw edge to the side seam, right sides together, and pin from the underarm to the shoulder. At the shoulder, lap the front end under the back.

3. Position the facing over the band. Align the facing edge to the armscye seam, matching the shoulder and side seams, and the armscye band edges. Sew the seam. Turn the facing to the inside; press the band away from the armscye.

4. Sew the underarm inserts. Cut four underarm inserts. Sew them together in pairs, right sides together, leaving an opening for turning. Turn each pair right side out and press. Attach the inserts inside the garment by sewing them to the facings; alternatively, make them removable by using snaps or hooks and eyes to hold them in place.

Judith Neukam is Threads’ senior technical editor.