Is it permissible to engrave images of zodiac signs on metals, without believing in them, but rather to fulfill a customer's request?

If engraving zodiac signs means placing pictures of complete animate beings (like the lion and the ram), then this is absolutely impermissible. However, if the intention is pictures of inanimate objects (like planets and stars), there is no objection unless they are used in forbidden astrology, in which case it is impermissible due to the cooperation in sin.