Capacitive Proximity Sensor - Detecting Metal

My idea consists of creating a capacitive sensor that is able to detect a conductive metal object (without human contact) through a 2mm glass surface. I have been using the CapSense library, not sure if modifications would be required to make something like this work properly.

Just want to get a general idea if anyone has had any success implementing something along the lines of the sensor described above. The sensor works perfectly fine for human contact which is expected but the capacitance does not seem significant enough when it is a metal object to sense through the glass surface and get a consistent difference between the two readings (with and without metal object).

Thanks in advance for any ideas/thoughts posted.

anonymous-jw: My idea consists of creating a capacitive sensor that is able to detect a conductive metal object (without human contact) through a 2mm glass surface. I have been using the CapSense library, not sure if modifications would be required to make something like this work properly.

No firmware modifications - capacitance is capacitance, however you look at it. This is the standard "studfinder" application (and I do not mean brawny males).

anonymous-jw: The sensor works perfectly fine for human contact which is expected but the capacitance does not seem significant enough when it is a metal object to sense through the glass surface and get a consistent difference between the two readings (with and without metal object).

And that is because the capacitance of a small metal object is not anywhere near that of a large human.

Also, the human has a large effective return capacitance to (indirectly, the Arduino) ground. In order to sense an isolated metal object, you require two capacitive plates, one for the sense terminal of the Arduino and a "reference" one to couple the object back to the Arduino ground.