Then I saw this post from Sew Many Ways where she used a hardware drawer from Home Depot to organize small items. PERFECT. So I went shopping, and here's what I found!
My new storage solution from Home Depot. It has a handle on top, and the doors snap and/or lock shut.
Just showing you what kinds of organization/storage I used. You can see what the containers fit well (Sephora eyeshadow, an older Maybelline eyeshadow, LA Colors and Hot Topic smokey eye palettes (not shown), Maybelline Color Tattoo, e.l.f. duos, some older Clinique eyeshadows) and what containers didn't fit so well (Sugarpill loose pigment was too tall, The Body Shop color cubes were too wide (though I could have taken them out of the big square and into the small cubes and it would have fit fine), old Hot Topic eyeshadows by Warpaint Beauty). The larger ones were a perfect height for my drug store liquid foundations, perfect length for anything that came in a tube or sticks of eyeliner (except the new Wet n Wild 99 cent color icon pencils), and large enough to handle anything that was just barely too skinny for my small drawers.
Then I took these pictures and went "hmm, I might have too much makeup!" No such thing, I know, but this is super convenient and super cheap. If you need a different solution, there are more compartmentalized storage solutions/cases at Home Depot for much cheaper than I have ever seen at any makeup audience store.