I used to use Thangles and loved loved loved it! Now I use a program called Print and Sew to make half and quarter square triangles--same as Thangles but you print them on your printer. This program makes sizes "before" you put them in your quilt--I learned the hard way too! :D It's better to do a test one just to make sure of the size. I can't make accurate half square triangles any other way. :-D