Iron Horse Ball is a key item in Resident Evil Village. It's meant to be placed at the labyrinth located inside the room to the right of The Duke at Heisenberg's Factory B4. Will give the Bister Skull. Inside the Foundry at Heisenberg's Factory MB4, requires the Ball Mold.
Resident Evil Village labyrinth puzzles and ball locations guide - Polygon
M1851 Wolfsbane, Resident Evil Wiki
How to Get the Iron Horse Ball: Item and Location Guide
Category:Resident Evil Village key items, Resident Evil Wiki
Heisenberg's Key, Resident Evil Wiki
Crystal Heisenberg, Resident Evil Wiki
All Resident Evil Village labyrinth ball locations
Cog Mold, Resident Evil Wiki
How to Solve the Iron Tower Labyrinth Puzzle
Iron Horse Ball, Resident Evil Wiki