My favorite way to store Cricut Cartridges is to use 3-holed zipper pencil pouches. My favorite ones are the ones I can get at the Dollar Tree or Wal-Mart for $1 each and has a clear window. I insert the overlay, booklet and cartridge in each pouch.
With this key ring in tact, you can now hang your collection(s) of cartridges from just about anywhere.
Instead of bundling them up all together and hanging them from this key ring; some have chosen to use these same pencil pouches, but store them in a 3 ring binder.