I recently created a flower pillow that included a recycled bottle cap. I smashed the dickins out of the bottle cap on my front-yard cement steps (also where I do my grommet work), created two holes with a large nail, coated it on both sides with spray primer, applied a couple coats of lilac spray paint, and finished off with a couple coats of poly spray. WaaLaa....a metal button!
I liked how they turned out - and would also like to try some decorative rub-ons on my next batch. My only problem is I don't drink anything out of bottles that have metal twist caps. But I've asked a few of my friends to keep their eyes open for any!
Oh....funny story - recently when I was in San Diego for a work conference, I was waiting in line in the hotel gift shop when a gal opened a bottle of soda that had a twist cap. She was kind of looking around for a waste basket and I offered to take her bottle cap. She looked at me with this quizzical look and I briefly explained about my new "button" adventure. She laughed, offered me her bottle cap, and then proceeded to ask me specifics about my process because she said her husband would love to try it himself! I wonder how many he's made by now?? :-)