I had my son do his all by himself, and he got thrashed. Not a big deal, but still.....i realized that there's nothing wrong with giving a bit of advice and help.

At the very least have your kid paint the darn thing! The paint does not affect performance unless you're putting on more than 20 coats. Have him put on a decal or two. Have him draw the design. Have him sand it down. Let him do some of the shaping.

It is kind of annoying, though, when a snot-faced kid shows up--he can't even tie his own shoes or button up his own shirt--and he has a perfectly shaped, weighted, painted, aerodynamic car. I mean, c'mon. Even a special needs kid can paint his car.