The original dowsing rods had to be a fork from a particular tree. That is WOOD. No they are also using coat hangers, whatever ... METAL.
Why not just lick your finger and stick it up in the air?
As I’ve said before, I can’t explain it - I just know it worked when I needed it. If I had to “dowse” for it, I couldn’t find piss in my own boot but I know people I would trust to find it.