I don't go through too much cornstarch, but the cornstarch I do use I keep in this jar. I have to refill it about every year. To do so, I go to Herb & Spice on Bank Street, which sells it in bulk.
It seems that the last time I refilled the jar, I noticed how difficult it was to get the powdery cornstarch into the narrow-mouthed jar with the wide scoop. So I scribbled on the bottom of the jar in permanent marker, "Need large mouth funnel to refill".
Good that I did, because in the time that had passed since I had last refilled my cornstarch jar, I had forgotten about the funnel requirement; however, after washing the jar and inverting it onto the dishrack, I saw the note and was reminded!
Ain't that clever?