Bells People... Use them!

A great many, even a small majority, of the children's bikes I see have broken bells - the bikes get knocked around and dropped and the bit you flick always snaps off, so reinventing the bell might not be as silly as it sounds.

I have a semi circular scar on my kneecap from a childhood encounter with the perfect bell, just after my first encounter at speed with a pothole.
One of my first subsequent modifications was to fit the bell upside down, but it filled with water and seized up, much like me knee has now.
Anyway when I need a bell these days I just say hello, excuse me, ding dong, etc