Trying to see if anyone here has been able wrangle a visit to the cockpit (not in flight of course) and if so, how were you successfully able to pull this off?

My 3-year old son and I have an upcoming flight coming up and he's already decided he wants to be a pilot (failing that, a carpenter or a fireman ) and it would be a dream for him if he could visit a live cockpit (apart from the DC-3 at the Smithsonian) and chat with the captain.

It's my opinion that this is close to impossible with NH (I asked a purser on a flight I took several weeks ago and was not successful) but I just wanted to throw this out here.

Thanks in advance