This is a project of wall wire detector based on FET (Field-Effect Transistor).
FET with non-connected GATE contact is able to detect electric field produced by wires supplying your lamps, TV and other.
If you want to drill a hole in a wall, you got to be sure, that there are no wires hidden at the spot to be drilled.
Schematic and case project included.
If you want, you may replace LED with headphone connector.

Prusa

Prusa Clone

No

No

0.4

77

Set good infill because of thin walls.