This quilt block is a common block and has many tutorials out there telling you how to cut out the pieces carefully and piecing them together.
Well with my Cut Down Method it reduces the pattern to a 9 patch. My method uses 4 Boston Blocks / 4 HSTs cut out my way and the center is a Combo 4 patch cut out my way.
I used a 3 1/2" template and the finished size is 9 1/2". If you want to make a 12 1/2" quilt block use a 4 1/2" template.