If you want something to explain itself you should choose something articulate.

I'm sorry; I really didn't think my idea was all that complicated. Let me connect all of the dots before handing it back out: Perhaps it could become an industry standard to install miniature metal detectors into microwaves in order to prevent the microwaving of metals, such as aluminum. I don't think it takes a giant stretch of the imagination to imagine someone accidentally putting the can of dog food in the microwave instead of the bowl of food, or failing to realize that the cover is aluminum foil, maybe a spoon slipped to the bottom of the bowl of soup, whatever. It would require a moment of idiocy but at least any further damage could be prevented, maybe a little alarm sounds. Furthermore, it could serve as a warning to younger users not to put metal in there; not everyone is born knowing not to put metal in a microwave.

I'm actually thinking right now that perhaps it might be cost prohibitive, relative to the situations it can prevent. Then again, I don't know how expensive it would be to miniaturize metal detectors, as I am not familiar with their function. Constructive criticisms welcome, as are pertinent facts.

I appreciate the elaboration but a metal detector surveying the inside of a box necessarily made of metal to isolate dangerous RF radiation presents something of a problem. It might be possible as an appliance exterior to the RF chamber but that would make the appliance somewhat larger.

The idea of placing a metal detector in the microwave is not new, I think the engineers who built the first microwave oven thought about it, the problem is that the radiations inside the oven would break the metal detector instantly, and some of the appliance parts too, and these can be very expensive, so I think this idea needs a little more research.