If needed, activate Ring of Valkas' equip ability by paying {1}, attaching it to Metalworker.
Activate Metalworker by tapping it and revealing at least four artifact cards from your hand, adding at least eight {C}.
Activate Urza by paying {6}, creating a token copy of Metalworker that is a 1/1 Soldier.
Activate Ring of Valkas' equip ability by paying {1}, attaching it to the Metalworker token.
Repeat from step 2 using the Metalworker token instead.
Once you have infinite colorless mana, you may target any artifact you control to get infinite copies of them.

Infinite colorless mana

Infinite copies of each artifact you control

Infinite creature tokens

Infinite ETB

Urza, Prince of Kroog

Metalworker

Ring of Valkas

Float at least {11}.
Activate Doubling Cube by paying {3} and tapping it, adding at least {8}.
Activate Urza by paying {6}, creating a token copy of Doubling Cube that is a 1/1 Soldier.
Activate Ring of Valkas' equip ability by paying {1}, attaching it to the Doubling Cube token.
Repeat from step 2 using the Doubling Cube token instead.
Once you have infinite mana, you may target any artifact you control to get infinite copies of them.

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