Things like air-brushing is very specific and imagine that he would have to concentrate on just that to achieve. Saying that there is definitely money in it as demand is relatively high in the right places. I was going to have air brushing lessons but the biggest place in the UK has a 12 month wait!!

If he wants to be more general the only way for it is free labour, as awful as it sounds but very few garages will want to pay for a saturday junior these days. If they do all he'll be doing is making tea and coffees!