This will be incredibly boring to anyone other than a workroom person seeking a faster way to sew encased cord to Roman shades. Plus, the pictures are not great.
This method evolved over the course of a bunch of identical shades. I won't say it's tons of fun, but it does streamline the process.
And so on! until it's all done.
In this photo you can see the weights holding down the area I'm not working on.