I use the little craft boxes they sell at Walmart. They come in many sizes and have little cubbies that are perfect for storing atties and cartos. I have a huge pile of them, with little ones I use to store filled cartos, with labels on the top to keep from mixing flavors. They wouldn't work well to go out with, but my little ego case works great for that, enough room for 3
batteries and 8 cartos which gets me
through a day or longer if need be.