The prototypes (Or what commoners would use) may not have been metal, since metalwork was probably rather pricy, (carved wood or unfired clay perhaps) and decayed over time. Only the “winning” design was made metal, until replaced. :)

Idk, really just spitballing, like I said I don’t think that’s actually what it’s for. I find it more likely to be an apprentice test object, kept as a status symbol. But we’ll probably never actually know.

This little blurb from the article is why I think it’s a training object

Parker says the piece was cast in “sticky,” leaden metal—making it difficult to mold—and was fragile in texture.

“A huge amount of time, energy and skill was taken to create our dodecahedron, so it was not used for mundane purposes,” writes the group, adding: “They are not of a standard size, so will not be measuring devices. They don’t show signs of wear, so they are not a tool.”