I've used many different methods to make half-square triangles in the past. When I started quilting I just used the formula of add 7/8" to your finished size square. Cut a square that size and then cut it in half on the diagonal and sew two triangles together and press open. My squares never came out square with this method though. I don't know if I was just not accurate enough with my sewing or pressing, but I quickly realized this method wasn't going to work well for me.
Then I discovered Thangles - the triangle papers. I used these for a queen size quilt that had a lot of half-square triangles in it. They worked well but then I had to pull off the paper and that was a lot of work. Plus it left little bits of paper all over the place, which didn't make me very happy.
My next method was to cut a square 1" larger than the finished size half-square triangle needed. Draw a line along the diagonal of one of the fabrics, sew 1/4" away from the line on each side. Cut on the line, press the half-square triangles open and then square them up to the needed unfinished size. This worked great, but drawing lines on 100 squares gets old fast.
Then I discovered the Angler 2. I love my Angler.
It can be a bit of chore to get it lined up right with the needle. It's a lot faster than drawing the bunch of diagonal lines though! Once it is set up properly and taped down, I can make a lot of half-square triangles pretty quickly. I still cut my square 1" larger than the needed finished size. I line up the tip of one corner with the appropriate line on my angler and sew. Then I just flip the square over and sew the other side. Cut on the diagonal, press open and square up.
I had to make 192 half-square triangles for the border of the Cub Scout quilt. Whew!
