Not really sad. The old fellow lived a good life and did what he wanted to. That's pretty darn satisfying!
Also, not many people can honestly go a Smithsonian Museum and point and say, "Hey, I built that!"
This guy aided in production of an ICON... It's more than just a TV show or a specific miniature. THIS IS AN ICON of American pop culture and history.
Again, very cool, but not sad at all in this case.
I'd say he did very well. Aside from very questionable studio decisions and some very greedy dealers, overzealous fans, and licensees, the show's influenced a lot of people to do good and excel in a variety of sciences.
That's something very good to be connected to. His friends and family should be very happy he was associated with that in some way.
What more could you want???