Q: What is the one thing that is most attracted to metal?
A: Well, a magnet, of course.
So you invent a thing called a magnetic stud finder. You place a weak magnet on a little flippy rod-thingy. Encase it in a transparent plastic box. When you drag the magnetic stud finder across the wall, the magnet senses the metal embedded in the wall and the little flippy rod-thingy moves.
One huge problem with this idea is that the magnet is not strong enough to really snap to attention when it senses screws or nails. It has to be right on top of the screw or nail in order to move. This means that you have a lot of sweeping and dragging across the wall to do.
The very instant the magnetic stud finder senses the fastener below, you need to be ready with your carpenter's pencil to make a mark on the wall. You did have your carpenter's pencil in your pocket, didn't you?
A better option is something called the Magic Stud Finder, which uses super-powerful rare earth magnets, or an electronic stud finder.
