But I am now doing the same thing for my earrings. this is what the system looks like:
When putting your earrings on the foam for the first time, just poke a hole through the foam with the earring post and attach it to the card. So easy!
The box I've used to store my earrings in is from Michael's. It is made for holding ribbon, but it works well for the earrings cards. However, you could use just about any small box. Just make sure that you cut the cards so that they fit snugly into it.