One of the great things about selling craft supplies on Etsy (as I do in my Crafty Green Magpie shop) is that sometimes I find out what people make with the supplies I sell!
I recently sold a whole load of plastic bottle tops to the owner of the OldsNewCrafts shop. My first reaction was one of great surprise as I had had these bottle tops listed in my shop for a while and no-one had bought any of them - I was literally going to give up on trying to sell them when this order came in!
I love the little gingerbread man she's already made with recycled bottle tops and look forward to seeing what else she makes!
If you wonder what to do with your old plastic bottle tops you can (if you're in the UK) take them to your nearest branch of Lush Cosmetics who will melt them down and make tops for their toiletries bottles. (This is what I used to do before I came up with the idea of trying to sell them on Etsy.)