I've had my eye out for a nice flour shaker for a while.
Don't know why I didn't think to do this earlier.
I just used a nail and a hammer to make the holes, probably should have drilled them, but I was in a hurry, once I think of a new idea I just want to do it right away. I figured I can always make a new one later if the messyness annoys me, I have plenty of those metal lids.
I had the jar already, and it's perfect, it's quite narrow so easy to hold and shake.