You control another nonlegendary artifact creature.
Mana Needed
({10} magic symbol) at most available.
Steps
Activate
Chrome Dome twice by paying ({10} magic symbol) , creating two token copies of another artifact creature you control with haste.
When the creature tokens enter,
Mana Echoes triggers, adding ({C} magic symbol) ({C} magic symbol) for each creature you control that shares a type with the creature tokens.
Activate
Chrome Dome by paying ({5} magic symbol) , creating a token copy of another artifact creature you control with haste.
When the creature token enters,
Mana Echoes triggers, adding ({C} magic symbol) for each creature you control that shares a type with the creature token.
Repeat from step 3.
Notes
The cost will vary depending on the artifact creature you choose and how many creatures you control that share a type with that creature. The above cost assumes you control no creatures that share a type with the chosen artifact creature. If you control more creatures, then start the combo at step 3 instead for maximum efficiency.
Results
Infinite ETB.
Infinite LTB.
Infinite colorless mana.
Infinite copies of artifacts you control with haste.