Do you have a garage at home?

If he wants to get into moddifiying, customising then my suggestion is to maybe buy a small project that he can work on - the end result being a car he will own when he passes his test that will make his mates SICK with envy.

He will learn as he goes, make mistakes, moan like fook, but it will be HIS project and HIS car. You may need to spend some £££ on materials and bits, but if he shows enthusiasm - which the more he learns the more he will, then it's all working towards the right end.

He don't want to prep it lol, well that is the crap bit, but the most important, so maybe watching shows like 'Overhauling, Wrecks to riches USA, Custom my ride - not pimp my ride lol!!.

These shows wont give him masses of knowledge, but lots of inspiration at what can be done. If he can get a weekend place in a garage then great, but he will learn alot through trial and error and reading up on how to do it, and practice.

Stuff like airbrushing, well this imo requires and artistic flair to be good at it, best way is buy and airbrush kit, read up on how to do it and then practice doing it - you have to have patients thought.

Mike lavalle is a guy to check out for some awesome inspiration

http://www.killerpaint.com/gallery.html

He is a teenager so going to be a bit hot headed and want it to be done now now now, in time with practice and knowledge he will learn it is all in the prep, the more work you put in the better it will be.