Clever ways of detecting screws behind stickers?

[kalel]

I'm wondering what clever ways some of you might have used, or heard of, for detecting screws under stickers or rubber pads.

Let's assume we are talking about cases where you can't easily see or feel the screw behind something. You don't want to tear those rubber pads or stickers unless absolutely necessary.
Is there a clever way to detect "hidden" screws?

The simpler the method (that is, without requiring expensive specialist tools), the better, but I'd like to hear about any.

[RGB255_0_0]

My fingers. For things like rubber feet I just rip them off.

[kalel]

My fingers. For things like rubber feet I just rip them off.

But sometimes this may cause damage, e.g. with a computer mouse, you can't always return it 100% as it was.
In other cases, the cheap or old rubber may tear in two pieces.

[RGB255_0_0]

If it's a cheap piece of crap and in warranty I'd just return it. If it's a branded product there's likely information on the web from places like ifixit, youtube or even service manuals and forums such as this one. Gently rubbing your finger over a warranty sticker should not affect your rights to return - only a damaged sticker should.

[capt bullshot]

In case the finger sensor doesn't work, you could try a magnet. Many screws are made of magnetic materials.

[amyk]

X-ray machine (ask your dentist if you don't own one...)

[Muttley Snickers]

In case the finger sensor doesn't work, you could try a magnet. Many screws are made of magnetic materials.

Just beat me to the post, I was going to suggest the same thing and providing the screws are not 316 stainless then a magnet will easily identify their location or pick them up, the local recycle center was clearing these screw drivers out for peanuts so I grabbed a handful, they incorporate a ridiculously strong magnet on the handle end, the colours are a bit too fancy for my liking but easy to find on the bench.

[Nusa]

Deductive logic...where should the screws be?
Feeling for screw holes under stickers.
A Magnet, for screws not buried in deep holes.
Seeing where surfaces will flex under pressure. Screw locations tend to be reinforced or have sturdy backing.
Finding and looking at teardown pictures/videos.
Asking others who might know.
Thermal or other imaging technologies may give some view of the interior.