

I think it’s unlikely to be a knitting tool, as you could achieve the same with a simpler tool.
For example, I’ve seen people saying it’s for wool gloves. But a bar with five holes and some knobs would do the trick, no need for an intricate form like a dodeca.
I don’t knit. I’m saying this based on multiple factors:
1. Videos of people who knit trying to use a dodecahedron. Like this one or this one. They use the holes, they use the knobs, but the core shape of the tool itself is practically irrelevant, and if anything it gets in the way. Also note the end result, it’s way crappier than a good knitter could do by hand. (I might not knit but I do see people knitting all the time.)
2. The existence of a similar icosahedron. It could be used just fine for cyphers, but not for knitting - note how the holes are too small. (Also, you wouldn’t need so many faces.)

3. The Romans assigned manual labour - like knitting - to slaves. And slaves aren’t exactly the sort of person a Roman would waste precious bronze with, specially not for a tool with an excessively specific purpose, like this one.
4. Wool production in Rome was mostly around Gallia Cisalpina:

And yet those dodecahedra were mostly found around Germania, Belgica, Lugdunensis, some even in Britannia:

If anything the distribution hints more something military.