Could you give some examples? I may be lumping the two types together, but isn't the difference that chrome is painted on while metallic is the color of the plastic that the mate is formed from. The reason I ask is because my reasoning for metallic was that all the blanks would have no paint on them to keep the cost down. Only the BAF and accessories would have any paint and even then the accessories wouldn't have more than a single color added where appropriate. As a couple of examples the Akuma hair would have the string painted, the machete would have the blade painted silver and the AOX Rogue hood would have the hair detail painted black (just to give Femme Fatale Lil' Red an actual hood and cloak).
Wasn't entirely sure what you meant by Metallic.
To me, there is Metallic -
And this is Chrome -
And I'd still want them to be blanks, but I like the idea of a chrome painted blank.