Help with prototype designing

[Talco]

Hello everyone,
I am interested in carrying out a small technological project and before starting it I want to make sure it is possible,
I will refrain from specific details about the project's purpose because I may want to register it as a patent in the future, but if I miss important information please ask me and answer as best I can.
The essence of the project is measuring how many metal objects make contact with the main metal surface, and in case of removing one of the objects, to create a warning.
My question is if there is a sensor that I can attach to the metal surface that will sample the surface tension at any given moment and know how to detect objects that are placed on it, of course, the metal object placed on the surface will be connected to a device too (preferably powered by a small battery) that will give the electrical resistance that the sensor will detect, do you know a product that can help me build the project or at least a prototype, is there a possibility for such a project? do you think of a smarter way to accomplish this project?
Thank you very much for your time and sorry if my questions aren't accurate or professional, this is not my main occupation.

 

[BradtheRad]

There is a hi-tech instrument that can detect an unseen break in a cable and its distance from the end. Another hi-tech store-bought instrument can 'see' through a plasterboard wall, just like radar, to tell the difference between wood, wires, and pipes.

Your project might work by sending a 'click' through the metal. Maybe a brief electrical or acoustic signal.
Then have a sensor listen for any echo or series of echoes. Or any resonating frequency.

Position the sensor in various places on the metal (close to the click generator and far from it).

Or try multiple sensors.

Or send various frequencies (electrical or acoustic) through the metal. Remove or attach an object and see if it causes any difference in response.

I'm not certain how 'hi-tech' you need to construct this project. Anyway if you make a million dollars, please be sure to remember me.