You control any number of mana-producing artifact(s) that enter the battlefield untapped and that can tap to produce at least ({R} magic symbol) ({R} magic symbol) .
You control at least three additional nontoken artifacts, including the mana-producing artifact(s).
Steps
Activate any number of mana-producing artifacts you control by tapping them, adding at least ({R} magic symbol) ({R} magic symbol) .
Activate Krark-Clan Ironworks by sacrificing any artifact except itself, adding ({C} magic symbol) ({C} magic symbol) .
Repeat step 2 for each remaining applicable artifact.
Cast Scrap Mastery by paying ({3} magic symbol) ({R} magic symbol) ({R} magic symbol) , causing each player to exile all artifact cards from your graveyard, then sacrifice all artifacts they control, then return all exiled cards from exile to the battlefield.
Repeat steps 1-4 one additional time.
Activate Codex Shredder's second ability by paying ({5} magic symbol) , tapping and sacrificing it, returning Scrap Mastery from your graveyard to your hand.
Repeat from step 5.
If artifacts you control can tap to produce at least ({1} magic symbol) ({R} magic symbol) ({R} magic symbol) , this combo nets infinite mana of those types.
If you control four or more other nontoken artifacts as this combo begins, this combo nets infinite colorless mana.