I have a Snap-On cart identical to the one in post #20. Had it for 30 years, still use it every time I twist wrenches. I have a heavy strip magnet stuck to one long corner with all my impact wobble sockets stuck on it (in order), plus flexible spark plug sockets.
It's a big time saver. Load the tools you need on onto it, roll it up to the car, then it's pretty much twist-and-grab as you're working, the cart right at your elbow, with only occasionally trips back to the tool box for something you may have forgotten. Also works as a light-duty, temporary bench for assembly/disassembly of components.
If I ever get another one it'll be a plastic. You can let a plastic one bump the car a little and it won't scuff the paint.