The machines disney use now do not simply detect metal. They will detect ceramics, plastics, carbon fiber, and differentiate a few basic densities of metal.
It also knows exactly where on/in your body the item is.
Cooler than that, without a human being looking at the scanned image, the AI will observe the scan and determine if the item is a weapon or not based on a model that is constantly refined via machine learning.
I watched a demonstration of the same machines (not actualy at disney) tell the difference between a real gun and an airsoft replica that was built with a metal barrel and nearly the same weight.
It knows the difference between a toenail clipper and a pocket knife.
It can tell the difference between 3 cubic cm of titanium in your hip and the same volume of gun barrel in your pocket.
What's going to blow people away is when they let the AI select ppl for more thorough screening based on body language and more esoteric markers like conversational semantic stress identifiers, word choices that indicate you are hiding something or worried about something.