I am also totally in love with this pattern. When I first started quilting, I saw one at a show & was completely enamoured. I have done tons of garment construction, including under arm gussets and really didn't want to tackle a lot of set in seams, so I just admired them from afar. Then at a quilt show, I got the Improved Jack's Chain pattern (don't be put off by the illustration).
http://www.quiltdesignnw.com/q140-ja...lt-pattern.htm
Which has
no Y seams, but still just sat on it. Then, I saw the 'Rock Around the Block' pattern in F&P. It's basically the same idea as the improved pattern, but set in blocks with sashing rather than a single chain.
https://www.quiltingcompany.com/stor...igital-pattern
I made the F&P pattern (linen background) first as sort of a practice run, then made the improved (dk grey background) still needs borders. Neither is quilted yet, I tend to piece at the cottage during the summer, then long arm in the winter. After making the first couple of blocks, I had some acrylic templates cut. I was then able to cut some of the pieces over large & then trim down. Once you get going it's pretty easy, but time consuming.
Let me know if you have more questions.