Drill extenisons let the player reach deeper Coal deposits in the Assembly line world. They can be placed in the Empty cavern below the Coal mine or where the tip of another drill extension enters.
Once built, the drilling direction must be specified (pressing the button with the red exclamation mark)
When the drilling direction is reached, it begins to transport the coal towards its beginning.
It's possible to build a chain of several drill extensions, as the player reaches deeper ground layers.
