Carpenters star is a great idea for a king sized quilt and would go together quickly if you make your block size (HST and whole square blocks) 8" or bigger. Plan on the mattress size for the center blocks part and borders to increase the size to drop on each of the sides. Consider whether you want enough quilt at the top to tuck the pillows under or have it just reach the top of the mattress because you put your pillows on top of the quilt when the bed is made.