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: Where To Find All 4 Labyrinth Balls
Well Wheel, Resident Evil Wiki
M1911, Resident Evil Wiki
Mermaid Ball, Resident Evil Wiki
RE8, Ball Mold - How To Get & Use
How to Get the Iron Horse Ball: Item and Location Guide
Iron Horse Ball, Resident Evil Wiki
Winding Key (Village), Resident Evil Wiki
M1851 Wolfsbane, Resident Evil Wiki
Sun and Moon Ball, Resident Evil Wiki
Ball Mold, Resident Evil Wiki
Heisenberg Factory Walkthrough & Map Guide Resident Evil Village (RE8 / RE Village) - GameWith
Wooden Animal (Head), Resident Evil Wiki
Heisenberg's Hammer, Resident Evil Wiki
LZ Answerer, Resident Evil Wiki