Renowned Weaponsmith does not have summoning sickness.
Steps
Activate Renowned Weaponsmith by tapping it, adding ({C} magic symbol) ({C} magic symbol) that can only be spent to cast artifact spells or activate abilities of artifacts.
Activate Pemmin's Aura's first activated ability by paying ({1} magic symbol) , untapping Renowned Weaponsmith.
Repeat.
Results
Infinite colored mana that can only be spent to activate abilities.
Infinite colored mana that can only be spent to cast artifact spells.
Infinite colorless mana that can only be spent to activate abilities.
Infinite colorless mana that can only be spent to cast artifact spells.