Thangles. My favorite method is to cut 2 squares, put them right sides together and sew 1/4" on either side of the diagonal. If you cut the squares 7/8" larger than the finished size of the block, you will end up with 2 identical HSTs when you cut along the diagonal line, hopefully the exact size that you need. There are several ways of determining the diagonal line which range from actually drawing it to eyeballing it to some gadgets that you put on the bed of your sewing machine. All of these methods are great for scrappy quilts.
As my friend Christine was watching me sew all of these individual squares. he suggested another method to make more HSTs at a time, instead of just 2. I started with two 8 1/2" squares, drawing diagonal lines across the wrong side of the lighter square and a vertical and a horizontal line. You sew 1/4" on either side of the diagonal lines and then you cut on ALL of the lines, ending up with EIGHT HSTs. It was a beautiful thing. Thanks CK for teaching me something new.
By starting with HSTs that are precisely the exact size, it gives me a better chance of ending up with points that match when I put my blocks together. I like that. I need that.
Now back to those 320 HSTs for my new project inspired by my trip to Barcelona.