Start with the pleather and elastic for the upper horizontal. Overlap the two pieces by ½” & sew together.
Repeat for lower horizontal pleather and elastic.
With the upper and lower horizontal pieces on your body or the dress form, center the harness halter piece over your neck.
Determine where the pieces should overlap. Attach with pins or a small piece of double sided tape between the strips of fabric.
Measure both sides off body to ensure things are still even and adjust accordingly.
Sew together. Try on and if there are any issues, pick the stitches out and try again.
Align the one end of the vertical piece with the bottom center of the lower horizontal piece. Align the upper horizontal piece with the vertical piece, so that the horizontal pieces are parallel. Sew together.
Align one piece of the V just below the right clavicle. Pin together or use a small piece of double sided tape between the strips of fabric. Measure to determine the right location for the left piece of the V. Pin together or use a small piece of double sided tape between the strips of fabric.
Try it on again and attach to the vertical piece.
Trim any excess fabric or threads.