That fits a bit. My nephew today told me, he would like a game, where he can draw a racecar (2D) and then be able to drive the car in the game. Sadly the demo is for faces only, otherwise I might have hacked something together to make it work ...
> where he can draw a racecar (2D) and then be able to drive the car in the game
If your nephew just would draw outlined 2D car side view, then its would be easy to convert it to 3D by extruding and in one two clicks export to supported format for game.
Just two apps needed: Inkscape + Blender
P.S.: If your nephew no need to play 3D game and top-view racing game (such as DustRacing2D[0]) is enough, possibly only Inkscape would be needed to draw top view of racingcar for game.
Yeah, I know, but his car designs usually also involve the front (it is all about the gimmicks, fire and razors and I don't know what else).
So a neuronal network would definitely not be able to make a perfect model out of it, but maybe enough to have a somewhat blurry version in tux cart for example.
But I will teach him blender soon, so we will get there eventually, but doing it automated, would be very cool, too ;)