Well since I currently have more GW paints than I know what to do with, I was having the same problem. Then one day at the grocer, I asked what they did with the containers pre-cut fish comes in, and they gave me one.
Plastic, snap-on lid. Holds many paint pots, and if one leaks, it doesn\'t spill because it is low height.
Really depends on how much paint and what kind you need to store, and will you be using it out of your storage container?
I know someone who stores paints in groups in pencil boxes. Those plastic ones about the size of a cigar box. He groups them in army schemes and such. He can grab one pencil box and have everything needed in it to paint up some figs on the go.
You could make your own as well.
Is your storage device for storing, using while you paint, transportation, or all/some of the above?