If you need a spanner but all the hardware stores are closed for the evening, you can actually take a bolt and a few extra nuts to create something that will work almost as well.
It obviously isn't quite as good as having an actual spanner on hand, but if you just have one little nut to tighten, this trick can give you that extra bit of leverage you need. Just screw two bolts onto a nut with space in between them, as shown above. The nature of the bolt means that it'll even be adjustable, which is great. This particular tip comes from a 1910 issue of Popular Mechanics, rehashed in their 110th anniversary look back. We couldn't find the original source (if you can, let us know), but Redditor Newkingdom has screencapped some of them at the link below.