Mox Opal

Metalcraft — {T}: Add one mana of any color. Activate only if you control three or more artifacts.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Mishra's Bauble

{T}, Sacrifice this artifact: Look at the top card of target player's library. Draw a card at the beginning of the next turn's upkeep.

Island

Mox Amber

{T}: Add one mana of any color among legendary creatures and planeswalkers you control.

Mm'menon, the Right Hand

Flying
You may look at the top card of your library any time.
You may cast artifact spells from the top of your library.
Artifacts you control have "{T}: Add {U}. Spend this mana only to cast a spell from anywhere other than your hand."

Sol Ring

Lotus Petal

{T}, Sacrifice this artifact: Add one mana of any color.

Darksteel Relic

Indestructible (Effects that say "destroy" don't destroy this artifact.)