Because I am that kind of geek, I have constructed a sort of EDC solution for tabletop roleplaying games.
For a long time, my only supply solution was a plastic case with dice and counters:
But that was never really quite adequate, and I wanted to be better prepared to leave home and run a game. I looked at toolboxes, but they didn't have quite the right compartments. I considered a tackle box, because those have lots of little compartments, but the options there are frankly overwhelming. Then I found a sturdy makeup case at a discount, and have assembled this:
In the upper right that's a GameMaster's Apprentice deck. (Actually three of them, including a couple of the neighboring trays, with different genre themes.) It's a surprisingly handy tool. Each card is packed with all sorts of randomized stuff that a GM might need in the course of a game: character names, memorable details, surprise encounters, et cetera. Plus of course die rolls. The graphic design is frankly a little hokey, but it is legible enough to work well in play. If I had to run games on a desert island with no other play aids, I'd bring the main deck.
The upper left corner is a stash of wound PennyGems, including a set of the jumbo 5/10 counters, specifically designed for counting hit points et cetera. I haven't used them all that much, but when I have they've been really handy, and they are nifty. The gray bag half-visible in the bottom right of the lowest rung of the case is a jewelry bag with lots of interior chambers, full of more different PennyGems. The creator of PennyGems has a fascinating site about their design: the graphics subtly representing different numbers are cunningly chosen. You can find comparable jewelry bags or as dice bags.
You can see glass beads and dice. I have a few sets of polyhedra dice (including one in metal, my favorite), enough matching d10s to play a character in a Storyteller or other game that uses dice pools of those, and a few sets of Fate dice which the sharp-eyed will recognize are actually old school Fudge dice, cast before Evil Hat released Fate. I need to rearrange things at some point to have more d6es because there are plenty of games that require throwing big handfuls of them.
In the tray on the lower left you will see some exotic dice of my own design. They are d6s painted with nail polish: matte black on three sides, silver on the other three, good for playing Lady Blackbird style games that rely on a coin-flip dice mechanic.
I have a ton of blank 3x5 cards in the bottom tier because I use them a lot in all kinds of games, especially Fate, which is my go-to generic system. There are some dry-erase cards in there, which are pretty great. They don't erase perfectly cleanly, so eventually they give up the ghost, but they make me feel less guilty than throwing out a bunch of cards at the end of the game. The binder clips in the upper tray are there to get cards to stand up, a trick I learned from Zed Lopez. Not pictured are some dry erase name tents I keep in the bottom tray.
The section with the organizer tabs has a few different decks of Fate play aids: Fate rules summary cards, an It's Not My Fault deck (which show up colorfully because I've color-coded the edges to make the different types of cards easier to keep track of), a pack of common aspects, blank Fate Accelerated character cards, and Backstory cards. Frankly, I've not yet experimented with the Backstory cards, which provide a formalized version of collaborative backstory chargen that I learned from folks at my old table., but I have them in the kit because I'm itching to use them.
On the right side in the middle is a stack of a few other generic play aid card decks I like. There are turn tracker cards, which I've used a few times to good effect, plus a set universal score cards that sometimes turn out to be useful.
Plus dry erase and regular pens, of course ....