Eye-level (no need to look up or down)

If you are observant, this one shouldn't be difficult to spot

This one can be found near the early "puzzle tutorial" area

When stuck in this game, it can be helpful to revisit puzzles you have already solved

From town obelisk, head towards glassworks building. When you reach a clearing, you will see a metal piece of machinery painted yellow. Once you see it, you should have no trouble lining it up.

You have to back up far enough that you can no longer see the texture of the metal and the path looks solid yellow.

-

Look for something resembling abandoned construction equipment

This one is not underground.

It is likely you passed right by it without noticing