A couple months ago I made the Swoon block and fell in love. But it is really a mock version of the Star of Magi block, which is based on an eight-point star grid system, and requires several Y-seams to joint the patches together.
It is a lovely block, but I found no detailed instructions on making it, and I had to figure it out all by myself. It was a fun but challenging process since I had never done Y-seams previously. Now, I have pieced tens of Star of Magi successfully, and I would love to share with you how I make them easily without any marking or difficult measuring/cutting involved .
My method was inspired and derived from Sharyn Craig and Harriet Hargrave. In their books The Art of Classic Quiltmaking and Quilter's Academy Vol. 4 - Senior Year, very detailed instructions are given on how to construct the LeMoyne Star in the no marking way. I personally dislike marking dots to indicate beginning/ending of 1/4" seam line because it slows down the piecing procedure, and introduces another source of error/imprecision.
A basic sewing machine that can produce perfect 1/4" seam allowance.
Some fine pins.
A fast-fade or water-soluble pen (Note: not for making dots...).
Thread nipper or scissors.
Dry hot iron.
A Quarter Triangle Ruler and a straight ruler with 45 degree makings would make the cutting fast and easy.
With white tone fabrics, use the triangle ruler to cut 2" wide strips, and sub-cut to yield 24 quarter-square triangles (8 for inner round and 16 for outer round).
With blue tone fabrics, use the straight ruler to cut 2" wide strips, and sub-cut to yield 12 diamonds (4 for inner round and 8 for outer round).
With yellow tone fabrics, use the straight ruler to cut 2" wide strips, and sub-cut to yield 4 diamonds.
With red tone fabrics, use the straight ruler to cut 3.5" wide strips, and sub-cut to yield 8 4-1/8" long rectangles. Then, use the triangle ruler to trim two corners to make the half-prism shape.
When Unit 1a and Unit 2a are done, you will have the following:
When Unit 3a are all done, you will have the following:
When Unit 4 are all done, you will have the following:
Now you are done:
Look at how the seam allowances spinning and fanned at the centre. It is flat and crisp!