See, now this is what I am thinking. Why couldnt they have taken skin and allowed it to grow where it would naturally.
Anyway, how they did it is rather primitive. The proper way to do this would be to create a printed scaffold of tissue using a 3d printer and then coat that in cells ad allow it to grow in a nutrient bath. Once it was mature enough, they would then graft it to the person's head. The only reason you couldnt just graft it to there would be because its hard to get proper nutrients and blood flow and it would likely die quickly. If you can solve this problem, than you will be able to print stuff, directly attach it and it will grow naturally; oh, and you will probably win the nobel prize.