You could toss your bottle caps in the trash, but that wouldn't be the most environmentally responsible option. There are plenty of crafts you can make with bottle caps -- including these fab projects, linked below.
Here's an environmentally friendly idea: pair organic yarn with upcycled metal bottle caps to make this unique snowflake-shaped bottle cap trivet. This pattern is beginner-friendly and easy enough even for someone who has never crocheted before.
Here's another bottle cap trivet; to make this one, you'll combine scrap yarn and bottle caps.
This hot pad is made using bottle caps and size 10 crochet thread. The pattern was designed by Dawn L.E. Riden.
This little pincushion is crocheted using scrap yarn and a plastic bottle cap.
At the About Family Crafts Website: Sherri Osborn has posted a variety of different crafts that kids can make using bottle caps and other craft supplies.
At the About Scrapbooking Website: Get some fantastic ideas for using bottle caps as embellishments for your scrapbook pages.