^ That usually works best.
Most case-specific stuff is either too small, or there way too bulky to be "portable".
I have an ego carry case for my back-ups, and leave my pencil box/insulin carry case (with cut foam sheets to keep everything in place) at home because it's just too big. You could try plastic boxes they use for fishing lures. I've seen that work out for leaving in people's glove box/center console.
But if you just need one for the ego-c itself and nothing else, you could look into cigar tubes.