Activate Krark-Clan Ironworks by sacrificing a nontoken artifact creature, adding ({C} magic symbol) ({C} magic symbol) .
When the creature dies, Farid and Nim Deathmantle triggers.
Resolve the Farid trigger, creating a Scrap artifact token.
Activate Krark-Clan Ironworks by sacrificing the Scrap, adding ({C} magic symbol) ({C} magic symbol) .
Resolve the Nim Deathmantle trigger from step 2, causing you to pay ({4} magic symbol) to return the artifact creature from your graveyard to the battlefield, and attach Nim Deathmantle to it.