The manufacture of these cases is chenming.
Thanks for the tip, Handruin. But if you look a little further, you will see that Chenming appears to be solely an American distributor/arm of
Chieftec. Their product showcase includes several variations on the theme, and they claim:
Chieftec is a full-service vendor, with complete manufacturing facilities Including own tooling making, stamping, coating assembly, and export. We do it all by ourselves to assure customers of best quality.
If you look at their worldwide network, it links together the threads I was looking for. So I think they might be the end of the chain. But now I'm uncertain of the origin of the cases I linked to :-?