Cultures and traditions are different in different places, even with gigabit internet and ubiquitous literacy.

Roman North Africa was thoroughly Romanized by the era these start showing up, and the eastern provinces were as well. The might be some cultural reason these show up where they do, seems likely, it's very, very dubious that this cultural reason had to do with metalworkers identifying themselves since the sort of Roman metal working technology and culture around it was actually very standardized across the empire at this time.

Well, the regions the dodecahedrons have been found were mostly not thoroughly Romanised, right? From https://en.wikipedia.org/wiki/Roman_dodecahedron: "at least 116 similar objects have been found in Austria, Belgium, France, Germany, Hungary, Luxembourg, the Netherlands, Switzerland and the United Kingdom".

No, that's not right at all. Those areas were all part of the Roman empire and thoroughly Romanized as well. They used generally identical Roman technologies in Britain as North Africa or Italy, spoke the same Latin, used the same building styles, clothing styles varied primarily by how many layers they wore, they had the same legal system, and shared Roman arts and culture.

Man of those countries speak Germanic languages now since they were invaded by Germanic speaking people after the Western Roman Empire collapsed, but there's still Roman ruins and old Roman cities to be found in all of those countries.

>spoke the same Latin,

It depends.

* yes, roughly the same Latin, and only in N. Africa & the Western European provinces, not the eastern provinces

Actually have they collapsed ? The Germanic king actually follow Roman rule practices. Strange argument I knew. Especially after the famous history of the fall of the Roman Empire.

Germanic kings in Spain followed Rome's legacy.

Why would they need knit mittens/gloves in North Africa?

I don't think they would, geographic frequency actually does make the knitting tool idea more compelling, though none of the dodecahedra show any sign of wear from use which makes the knitting tool hypothesis sound unlikely - if the dodecahedra was a tool it wasn't used frequently at all. I don't think any hypothesis is all that compelling, they are very much a mystery.

> culture around it was actually very standardized across the empire at this time.

We really have no data at all to back such a claim.

We barely even know anything about how metalworkers and other skilled craftsmen organized themselves back in those days in any part of the empire