If you're like me - I love setting blocks on point and equally love changing patterns around - check out the Fons and Porter Easy Diagonal Sets ruler. I'm not normally one to have a ton of specialty rulers, but this one I consider a must-have - the price has been well worth the saved aggravation for me! It does corner and side setting triangles; just follow your finished block size (ie: 12") and it tells you to cut 9" strips for your triangels - the ruler has the angles, you just lay it on your strip and cut, flip the ruler and cut again. IIRC, I got mine at Joann's with either a coupon or when they had their Fons and Porter stuff on sale.