In case this helps somebody down the road:

I've been hunting a very small buzz from somewhere in the dash on bumpy roads. I could replicate it by hitting the passenger side dash from the top.

After some trial and error, I isolated the problem at the contact points at the passenger's footwell between the foot vents and the rest of the plastic assembly.

A couple of strategically placed cardboard pieces eliminated the noise until I buy some proper felt tape or something.

Cheers.

 

I can’t thank you enough for posting this. I’ve had the same rattle for over 4 years. A couple months ago my wife helped me diagnose it and she also pinpointed it to the footwell. When she raised her legs/ankles against the bottom of the dash it would instantly stop. However I never actually bothered to fix it. Now thanks to you I know exactly what to do!!!

 

Exactly = have her ride and raise her legs/ankles against it all the time.

I have a couple rattles, but was too lazy to try and explore, thanks for the tip Ill check it out