How do I find a missing tool trapped behind moisture-resistant drywall?

I had a similar panic with a torpedo level on a kitchen remodel and spent three hours convinced it was sealed behind a cabinet run. Before you start cutting into that green board, go check the most ridiculous spots one more time—behind the toilet in the other room, under a pile of scrap, or even in the fridge. Half the time, your brain just goes on autopilot when you're tired and you set it down somewhere 'safe' that makes zero sense later. If you're absolutely certain it's in the wall, don't just guess where it is based on memory. A **rare earth magnet** or a strong neodymium magnet is your best bet for finding it through the rock. Most self-leveling lasers have a decent amount of steel in the internal gimbals or the mounting plate on the bottom. Drag the magnet slowly across the surface in a grid pattern. You'll feel a distinct tug when you hit the casing. Moisture-resistant board isn't thick enough to block a strong magnetic pull, so it shouldn't interfere with the search at all. If the magnet doesn't pick up anything, try using a **borescope camera**. You can get cheap ones that plug into your phone for thirty bucks. Since you allready have your electrical box cutouts and plumbing holes, you can snake the camera through those existing openings and look down the stud bays. It beats the hell out of cutting 'exploratory' holes that you'll have to patch and sand later.

And honestly, if it is back there, you need to get it out now. Don't leave a two-hundred-dollar tool for the next guy who renovates the place in twenty years. It only takes ten minutes to unscrew a single sheet of rock if you haven't started taping yet. If you find the right stud bay with the camera or magnet, just back out the screws, lean the board out, and grab it. It's much less work to re-drive a few screws than it is to fix a botched mud job because you tried to be surgical with a drywall saw.

Reminds me of '92 when I buried my favorite Stanley hammer behind a cedar closet. Didn't realize it til I went to hang the door. Listen, if that laser is turned on, wait until the sun goes down and kill the lights in the bathroom. If you didn't get the seams tight yet, you might see a faint glow bleeding thru the gaps or out of a junction box. Used to find my chalk lines the same way back when we used those bulky old lamps. If it’s off, just pull the screws. Better to spend twenty minutes re-driving screws into green board than to let a perfectly good tool rot in a wall cavity.

Forget the magnets for a second. If you're running a Bosch GLL-30 or one of those DeWalt 12V Green Cross Lines, the housing is mostly high-impact plastic and non-ferrous alloys, so a magnet might just slide right past it. Get your stud finder—specifically somthing with a deep scan mode like a Zircon HD900. It’ll flag a density change for an object that size easily. Also, check the floor by your miter saw. I once spent an hour hunting for my PLS 180 only to find I’d used it as a shim for a wobbly sawhorses leg while I was cutting trim. If it's in the wall, just pull the screws. Better to re-sink a few 1-1/4" coarses than bury a good tool.

If you relly think it’s in there, go grab a Klein Tools ET160 Borescope. I’ve used mine to find everything from lost wire pulls to a tape measure I sealed behind a soffit. It’s got a 10-foot cable that’s actualy stiff enugh to maneuver, unlike those cheap generic ones that just limp out on you. Just pop it through an existing outlet box and you’ll see that laser clear as day. Better to spend a few bucks on a solid tool you'll use again than to play guess-and-check with your drywall saw.