Roadside Survival Bag
Once you've got everything assembled, buy yourself a good storage bag. We recommend a "dry bag," which is used by kayakers and canoers. It's very durable and totally waterproof.
Tip: Buy something spacious, with a little extra room so you can add extra items as needed.
A lot of drivers used to carry around a handful of extra fuses. But most modern cars now have at least one or two extra fuses stored in the fusebox. And, if worse come to worse, you can always steal a fuse from your radio to run your windshield wipers.
As for other spare parts, it's our humble opinion that, these days, there's no longer a real need to bring anything along for the ride. Nearly every town of any size has a good parts store with a decent supply of belts and hoses.
The only exception to this rule? If you're driving an unusual car like, for example, a Fiat. And you're taking it someplace equally unusual, like, for example, Saskatoon.