NieR: Automata features a vast array of crafting materials needed to upgrade weapons and pods. While many become readily available later, acquiring them early can significantly boost your character's strength. One particularly rare material is the Machine Arm. This guide details the best strategies for obtaining them.
Machine Arms have a chance to drop from defeated small machines, with higher-level enemies yielding a better chance. Early in the game, this makes them scarce. To increase your yield, focus on quickly eliminating large numbers of machines.
After completing Chapter 4, and your first encounter with Adam, a convenient farming location unlocks. The arena where you fought Adam will continuously respawn enemies, including numerous small machines. Access this area via the Desert: Housing Complex fast travel point and proceed deeper into the ruins.
While the machines here aren't high-level, resulting in a low Machine Arm drop rate, the constant respawning makes it the most efficient early-game farming method. This location is also excellent for farming Titanium Alloy. Using a Drop Rate Plug-In Chip can slightly improve your chances.
The following section contains minor spoilers for the final playthrough of NieR: Automata
During the final playthrough as A2, after the village robots are destroyed, you can choose to erase Pascal's memories. This allows Pascal to return to the village as a merchant, stocking various items, including Machine Arms, until the game's end. Pascal's inventory includes: