I would like to recommend the Triangle Square Up Ruler by Quilt In A Day. This ruler is so easy and fast to use. It allows me to square up my triangle before it is pressed. Wowzer what a time saver!!!! There may be other rulers like it out there but I am not aware of them. I am teaching a class tomorrow with lots of half square triangles. I have taught this class before and the quilt shop owner ordered a dozen of these rulers. She sold them all the first day! I asked the quilt shop owner where I am teaching tomorrow to order the rulers. I checked with her today and she elected to not order them. I am so disappointed but I have my ruler to show the ladies and they can order one on their own or ask her to order them one. No matter what method you choose to sew your triangle you can square it up with this ruler plus it comes with a handy dandy chart. Love it!