This guide details the methods for acquiring Filler Metal, a crucial upgrade material in NieR: Automata. Its scarcity necessitates a strategic approach.
Filler Metal is a rare drop found within the Factory area. Its spawn location is randomized with each playthrough, and its drop rate is notably low. Accessing the Factory: Hanger fast travel point (unlocked after progressing through the main story) is highly recommended for efficient searching. Note that you may need to unlock this access point again depending on your story progression.
While movement speed boosts can marginally improve farming efficiency, reliable farming remains impossible. The most practical approach is to thoroughly explore the Factory, collecting all naturally spawning items. However, purchasing remains the more efficient method if you have sufficient funds.
Filler Metal is exclusively sold by the Shopkeeper Machine in the Amusement Park. However, this becomes available only after completing all three playthroughs and achieving one of the final endings. Using Chapter Select to revisit the Shopkeeper after completing the game will allow you to purchase Filler Metal at a cost of 11,250 G per unit.
Despite the high price, purchasing is significantly more reliable than repeatedly scouring the Factory. Given the necessity of Filler Metal for crucial Pod upgrades and the need to reach maximum enemy levels, purchasing is often the more practical solution for late-game players.