I use a "car garage" for mine, that I bought at Walmart. I also store my alphabet sets in one. I'll attach a picture below (sorry, don't have a picture of the one that I store the ink cartridges in, but you'll get the idea). The spaces are even big enough to hold the jumbo ink cartridges. And, the car garage, is double-sided, so if you are lucky enough to have LOTS of cartridges and reinkers, you can hold lots in one case.
This tip of mine (for the alphabet sets) was actually published in the last Stamp It! magazine!