That is one of the coolest things I've ever seen, not to mention one of the coolest "Parent doing something nice for their kid" projects.
The closest thing I can think of is back when Alien Nation was on television, my daughter was 6, and she really wanted a Tenctonese (alien) baby doll. There WERE no Alien Nation toys of any kind, much less a baby doll. So I went out and found a relatively cheap baby doll with painted on brown hair. I carefully shaved off the ears and used laquer thinner to remove the "hair" in places to create the brown spot pattern the aliens had. Needless to say, she was thrilled with the doll. She carried it everywhere, even after the show was cancelled, and was constantly asked by people where she got the doll. She is now in her twenties, has her own kids and still has the doll... and still tells people what it is and where she got it.
Morninman is right... your son will tell his kids about the door you made for him.