How does the interior air vent system in a car work? How is it laid out?

[kanshou]

I was installing an ipod adapter and when putting a panel back in I suspect a little metal clip fell down into the air vent. It's an accord and it's the pair of vents between the dashboard and glove compartment.

Mostly wondering how the "plumbing" is laid out and if it's possible to get the little metal piece out.
The vents go straight down but if it banks back up to the windshield (right, right, the defogger) it might be possible to get it with a magnet on a stick.

 

[RockyD7]

If those two hoses go to to the windshield then you can follow them to the 'Y' where they come together to the main air vent line. That's where your clip will usually stop. If it falls further down and gets hung up in the heater core area then it's harder to retrieve, unless you can get one of the panels off the heater core.