I just finished a mystery quilt that called for over 400 half square triangles. I used a method whereby I doubled the size of the unfinished square (3.5x2) added 1 inch (7+1=8) cut 2 8" squares laid right sides together, used the Fons & Porter quarter ruler to mark corner to corner, sewed along each, cut on center, & and cut across at half way & up an down at half way. Opened them up, trimmed to 3.5" & had EIGHT perfect half square triangles & all 16 stars have perfect points. There is a tutorial on this somewhere, try YouTube, this method s GREAT for large quantities f half square triangles.