I made these last year, but continually found little ways to improve on the file. First it was too skinny, then it was too fat, then it was too squat, then too plain. Since taking this picture, I also added a springy pipe cleaner at the top. I think I'm done (for now).
There was a question about the stem attachment. The four sides of the stem slip into the slits at the top of the center piece and it just stays there. I didn't even glue it. You could cut the notches a little longer if needed.