On the basic block, square down from the apex of waist darts.

Draw the straight neckline on back and the halter one on front (details in next step).

Focus on the neckline:

• on back, draw a parallel line (3cm away) to the original neckline and cut the band away + draw the strapless neckline with two parallel lines 5-7cm apart
• on front, draw the two parallel lines first (from the armpit to center front), widen the shoulder dart by 1cm at the new neckline, then draw the collar line. Keep the measurements consistent with the back ones.

Once you separate the pieces, this is what the back should look like.

Do NOT throw the piece that you removed.

And this is what the front should look like.

Get the neckline pieces and identify the position of the original darts. We will close them and we will merge the back collar with the front piece joining them at the shoulder line..

This is the manipulation of the neckline pieces:

• back band with the dart closed
• front neckline with dart closed and full collar piece (see in red the notches of the shoulder line, where we matched back and front).

Now get the dress pieces.

On front, drae a slanted line 14-15cm long 8-10cm below the waist.

Cut all the way through the slash lines that originate from the darts.