Crosspiece is one of the method used to sew neck. Crosspiece requires only a small piece of cloth. Crosspiece means cutting the cloth in the cross direction and not in the straight direction.
Take a cloth crosswise and pull it on both sides , the cloth expands but when you pull it straight the cloth will not expand because the threads are aligned very close without any gap. When you pull crosswise the cloth expands because there exists some gaps between the threads.
We use cross piece so that the cloth can be expanded to the maximum and can be attached to the neck . If the cloth is cut straight then the cloth will not expand and so we have to cut large length of cloth. To avoid this we use cross piece. For sari blouse , cross piece is the only method used for neck. No other method is appropriate to indian sari blouse.
In the image below , take the cloth to be cut. Draw parallel lines of distance one inch (beginners use 2 inch distance) in a cross way manner and not straight.
Use marking chalk to draw lines and then cut along the lines. Join all pieces together. Next fold oneside and stitch throughout the piece. After you fold one side, the unfolded side of the crosspiece have to be attached to the outer neck (view part or front part).
The image shows you how to attach the unfolded end to the neck. Put stitches close to the unfolded end.
After you attach the unfold end to the neck again the crosspiece have to be folded like closing the note book. Put stitches on top of it. See the diagram below.
After you fold the cross piece like closing the note book again you have to fold the cross piece once completely into the inner part of the cloth. This is the final fold and the neck is ready after this fold. In the diagram below i've folded the crosspiece to the inner part of the dress and stitches are been put on top of it.