I have to go with Kay England's NIFTY NOTIONS RULERS - If your LQS doesn't carry them you can go to her website. She also has DVD's on using them. Half Square and Quarter Square etc. Other people have copied but I like the colors on her rulers better as they are easier for me to read. Will replace the Omni's I have as soon as they wear out. Best thing is almost no fabric waste & at these prices!
Have you tried the Altos cutting system? Check them out on line with the accurate strips I cut with those. I don't have to recut or square anything. Just sit and sew. If I sew straight perfect corners mist every time. :thumbup: