Many years ago, I built a kit car - a 30s-style MG sort of thing, using Morris Minor parts, mostly.
There were some quite nice wire-wheel style wheel covers available at the time, but only in sets of four, which was a shame, as the spare was exposed and a fifth one would have been nice, but the manufacturer/importer would not be moved on supplying a single, so I resolved to make a cover for the spare, rather than buying eight and having three left over.
At that time, my road was notoriously potholed and, before I started to sort out the cover, I was working in the front garden one day and was very nearly hit by a flying wheel cover.
It was an exact match for the four in the set that I had just bought.