Stud finder on a chain

I have a store-bought, brand-name stud finder, but it is pretty much worthless finding studs in anything but new-work drywall. I’d heard about using a magnet, I tried it, and I was sold. As shown in the drawing, I took the idea one step farther by adding a length of brass chain (non-magnetic) like the type used for old-style toilets and a brass ball (for a pull-chain fan) at the end of the chain.

The beauty of this setup is that I can swing the magnet back and forth, and up and down in a slow, wide arc, and when a steel fastener is found, the magnet stops dead in its track. Then I drape the chain down the wall. When it stops swinging, the chain shows the center of the stud (usually). After that, I measure the stud centers (usually 16 in.) and start the process over again.

By the way, the magnets I use are from old computer disk drives. They are super strong. I attach the chain to the magnet with epoxy. I usually keep a couple of these stud finders with me—not because they break, but because when somebody else sees me using mine, they want one.