Chief Engineer

Artifact spells you cast have convoke. (Your creatures can help cast those spells. Each creature you tap while casting an artifact spell pays for {1} or one mana of that creature's color.)

The Cyber-Controller

When The Cyber-Controller enters, each opponent mills X cards. Put all creature cards milled this way onto the battlefield face down under your control. They're 2/2 Cyberman artifact creatures.
Other artifact creatures you control get +1/+1.

Palladium Myr

Vedalken Engineer

{T}: Add two mana of any one color. Spend this mana only to cast artifact spells or activate abilities of artifacts.

Grand Architect

Other blue creatures you control get +1/+1.
{U}: Target artifact creature becomes blue until end of turn.
Tap an untapped blue creature you control: Add {C}{C}. Spend this mana only to cast artifact spells or activate abilities of artifacts.

Foundry Inspector

Artifact spells you cast cost {1} less to cast.

Jhoira's Familiar

Flying
Historic spells you cast cost {1} less to cast. (Artifacts, legendaries, and Sagas are historic.)