Plain open collar

Join front and back bodice at the shoulder. Measure the neck line.
A-B = half the neckline measure. Draw perpendiculars from A and B
A-C =3½” or to taste.
B-D = A-C. Join C-D.
G is midpoint of A-B
B-E = about ¾”
F-D = about ¾”
Join F-E
Draw the curve A-G-E