Can anyone suggest a use for

plastic milk bottle tops? You do know the sort I mean? Those red or blue or green or yellow or white or perhaps purple or black or orange plastic tops that seal those plastic bottles which contain milk - or perhaps orange juice.
I wanted a rubber band yesterday. They are kept, along with string and twist ties and jam covers and assorted other things in the bottom drawer in the kitchen bench cupboard. It is some time since I have needed anything from there, a very long time. I must have opened the drawer last year some time when I was making the marmalade.
The drawer was filled with milk bottle tops.
"What are these here for?" I asked my father. (He was sitting at the kitchen table drinking tea and gloomily reading the budget predictions in the newspaper.)
"Oh, don't throw them out. I thought they might be useful."
"Useful for what?"
"I don't know - but don't throw them out. They might be useful."
Right. Might?
I take out one of the 'barrier' bags I collect when shopping at the local greengrocer and fill it with the milk bottle tops. I deposit it silently next to him.
He finishes his tea, folds the paper and is about to wander off when I say,
"Are you going to take the tops with you?"
He takes them.
This morning there is a red top, a blue top and an orange top on the sink. I think the darn things multiply. They have a life of their own.
I collect another barrier bag and tack it to the corkboard and put the tops in that. They have been saved - rescued if you like.
Now, please - can someone tell me what to DO with them?