I used this one: https://blog.japanesecreations.com/how-to-make-the-perfect-summer-mask-origami-fold-breathable-very-easy-to-make, but skipping the initial folding stages because I was already starting with a double-layered rectangle. I had to adjust the sizes slightly because I had a bit less height that the pattern suggests, but I have a small face and they fit on my nose and chin OK.