I would contact Wargames Factory if you need to liaise with Chinese sweatshops, or Renedra. Wargames Factory is Dreamforge's manufacturer, and Renedra made the best Mantic plastics, which ironically were the first sets.
For metal spincasting, I'd contact Pendraken, Copplestone, or Perry twins. Interestingly, Perry twins cast 4000 miniatures specially sculpted for Peter Jackson for his Anzac Day exhibit this March.