My own Black powder storage is likely very illegal, considering WA State's law of 5# on premises, and that is just Black Powder.
My powder is stored on a closed door shelf over my reloading bench.
(I was really hesitant to show these following pictures because there's a bunch of other reloading "stuff" in the picture. I used to be a recognized shooter in the long-range Silhouette program while shooting AA Class, and I shot and loaded a lot, still do on occasion, especially the 45-70, and a particular .35 Whelen Custom I built back in Gunsmithing School over 25 plus years ago.
To say I'm a "experimenter" with about everything that shoots would be something of an understatement.)
Still yet, for the past 30 or so years my main interest in shooting ls with all the Muzzleloading Rifles, and making them shoot as well as possible!

Here is that shelf door open... there are 7 cans to the row, except the Swiss on the left, only 3, and the four "other" cans on the far right.
Our own Beaverman, and the Green River Mountain Men is a BIG reason I still have a nice collection of powders. Beaverman used to stop by on occasion and change out four, or five pound of one grade for another, depending on what I was experimenting with...On a halfway good day, I can go through a pound of powder every day, if I'm practicing for a Match, or trying to get a particular gun to shoot just right for me, maybe a little more than a pound....
The last couple of years has been up and down insofar as my health, and that's another reason I have so much powder on hand.
Some of that powder has a price tag of $17.95 on the can, and that speaks for itself....Jus'sayin

You don't know how many times I wished I still had that refrigerator I mentioned in the above post..it was truly the cat's meow!