I finished the thumbs on my mittens. They look a little funny and triangular but they are crazy warm and functional so I'm happy. I realized when I started putting them together when I decreased the number of stitches from the pattern, I forgot to decrease the number of stitches for the thumb itself. As a result, the thumbs would have been giant if I made them the proper size. The problem with that is that I didn't have enough yarn left for giant thumbs hence the triangular shape as I had to shrink them down pretty quickly. I think the second attempt (one on right) turned out slightly better.