OOH OOH OOH I am actually qualified to answer this! I’m a former makeup artist, and my kit was monstrous at one point. (I have since retired since brides are terrifying.) Here’s what I did to get it a little under control. First, my kit was a toolbox. On wheels. You need a lot of space.
Then, I got a couple of clipboards with storage. Something along these lines:
Then I went to the craft store and got magnets-by-the-sheet, cut it to fit the inside of the clipboard, and superglued that shit down.
Then I pried everything that had a metal pan (this would be most shadows, blushes, and almost anything in a powder form) out of its giant original packaging and grouped it by type of product and by color on the inside of the clipboard (magnet+metal=secure makeup). What was once fifty or sixty separate products was now three clipboards.
For stuff that can’t be repackaged, I had a million various Ziploc bags, with like items grouped together. High gloss lip gloss, matte lipstick, liquid foundation, eyeliner, etc. Brushes, sharpeners, tools, and the like all had homes in one of the toolbox drawers together. Mine also had little compartments, presumably for screws and small hardware, and I used those for bobby pins, disposable applicators, and tiny stuff that would otherwise get lost or filthy.