CVS has some Q tip looking things in the makeup isle, they're tougher than Q tips, one side is a bulb and the other side is pointed. They work great for cleaning hard to reach areas, painting the markings on an AR lower, applying cold blue, etc. You guys that are married or shacked up might have some on hand, but remember, the makeup box is her version of your toolbox - ask first.
Speaking of getting in trouble with the lady, in a pinch, tampons make pretty good bore mops for shotguns.
The glad storage things that Hillshire Farms sandwich meat comes in are great for holding small parts, are stackable, and best of all, are basically free after you eat a big sandwich.
I'll cut small holes in the top of said glad storage things to drain the last little bit of motor oil out of the bottle. It adds up quicker than you think. But on the other hand, I am the family mechanic, own three high mileage vehicles, and do a lot of driving, so it may not add up as quick for you...
I outgrew a tool box I got as a gift several years ago, and when I replaced it with a bigger box, I used the top box for gun tools. Its similar to
this one. But its a little weird having gun tools in a box covered with stickers from companies such as Edelbrock, MM, Holley, etc.
I used to keep old shirts and towels and such for gun rags, but between cars and guns, I wasn't wearing clothes out fast enough. I've just got to where I use disposable Kimberly Clarke Shop Towels.