The trick to making a great block is… an accurate quarter inch seam!
To test out your seam allowance:
Using scraps, cut 3 rectangles 2 1/2” wide x 6 1/2” long. Sew them together (on the long sides). Press & measure. The piece should measure 6 1/2” square. If it measures skinnier or wider than 6 1/2” (sewn width) adjust your seam.
And starch! Especially when cutting on the bias…
I made both the 12" and 6" - everything is cuter when it is smaller!