The fake-collar top

There were some questions about the top I wore with that big skirt in the previous post. Of course, I'm happy to post a clearer of it and I thought it might be nice if I would try and explain how it was made. 
In fact, I've made a couple more tops recently. All of them have some kind of unusual but simple to make detail, so I may just make it a bit of a series. 

This is the top in question:

A very simple shape: Fitted body with the extended shoulder line forming cap sleeves (if you make this shape based on a knit sloper or a tried-and-tested t-shirt pattern, raise the tip of the shoulder by 1 cm, extend it by about 8 to 10 and square down to 3 cm below the bottom of the original armscye).
Only the neckline decoration makes it different.
It's simple enough to make if you have experience sewing sharp corners:

First, you determine where you want your finished neckline. I went for a V-neck which is wide at the shoulders and fairly shallow at its tip. The angle at the tip of the the V is 90 degrees.
Then, you draw in a line at the width of the neckband, the red line in the drawing. Mine is 2.5 cm wide.
Measure the top of the neckband, the black line, and subtract 10%. Then, you can draft the neckband like this:

The number you've just measured and calculated will be the length of the dotted line. From there, angle up and down at 45 degrees to form the center front line of the V. The open end in the drawing is its center back, which will be cut on the fold. 
When sewing the neckband, stitch that center front line first (I use a small normal stitch on the sewing machine), press the seam open and then fold the neckband in half along the dotted line, right side out. To sew it on to the top, I carefully sew the point in place using a small straight stitch on the sewing machine (this is necessary because you have to clip the seam allowance on the top to move the fabric around that corner), and then pin the rest of the neckband in place, distributing the excess material of the neckline evenly on the band and serge it while stretching the neckband to fit the neckline .

For the contrast piece, you draw and extra line in the design, the blue one. In my top, the cream white band is 4 cm wide and it reaches to 2 cm from the point of the V. It is made from a simple straight strip of jersey (you need to use a fabric which will stretch properly. Recovery isn't very important for this. This cream white cotton knit I used has no recovery at all but in this design, that doesn't cause problems). To determine the length of the strip, measure the top edge of it, so along the red line but starting 2 cm from the tip of the V. This pattern piece is also cut on the fold.

When sewing the top, start with the shoulder seams, then carefully sew in the front corners of the contrast strip. After that, you pin and then serge/sew the strip to the top, stretching it to fit and then you apply the neckline as described above. Side seams and hems can be made either before or after you work on the neckline.

I hope this explains the neckline detail I made. It's not really a proper tutorial but I didn't take pictures while sewing. As mentioned before, if you've sewn corners before this shouldn't be difficult. I don't recommend using this detail on a garment with serious negative ease. In that case the corners may create weak spots in the fabric. 

Good luck sewing!