This post is long overdue. I was away in August and was asked to explain how I make these Liberated Stars. I know there are lots of online tutorials and of course, all of Gwen Marston's books, but my friend wanted more about the measurements vs the method. I hope this helps and if you have any questions, do not hesitate to ask in the comment section.
This block needs to be finished at 5 1/2" so unfinished at 6". This is a lousy size for a 9 patch block as the numbers are not easily divisible by 3. SO......I start with 2 1/2 " strips, cut them down into 2 1/2 " squares and then make my star.
No worries, as we are going to trim up this block to 6" unfinished. Notice how I have the ruler lined up to the center block and there is overhang on both sides of the block. I've got the horizontal and vertical lines on my ruler lined up to make this block straight and square. See how the center blue square lines up as a 2" square.
This block finishes at 12" so for the big star, the 9 patches I start with need to be 4 1/2". To make the center star, this is a weird size for the 9 patch. Finished, the center block 9 patch would be 1.33". Not the easiest measurements to make. For this block I started with squares that were 2" so my center block was 5" unfinished and I trimmed it down to 4 1/2", using the same steps as above.