At long last got it done! It was quiet challenging because I've never sewn any needle books before. Had no tutorials but an idea how it could be made. The first attempt failed completely. You can imagine it wasn' t really satisfying. Next try. Everything seems to be done right. Yes, I can.
front view
inside
re-used old curtain hooks to insert floss (and you can even close the hook so your floss doesn't get lost!)
I'm not a magician, I'm a pupil :)