"...his interest lay in custom design."
Without knowing precisely what type of work/career he has in mind, here's what I've suggested to a lot of folks during the past 29 years(and if they can't do it themselves or arrange for assistance to get it done I've done it for them.)
Contact some of the businesses where he would like to work and ask them for training recommendations. Get out the Yellow Pages if you have to and tell the person who answers the phone you aren't looking for a job, just training and work experience requirements.
Does he want to do hands-on vehicle design AND modifications? Does he know how to weld, paint, rebuild an engine and do upholstery? Will he need to know basic, intermediate and advanced machinist's skills in order to produce practical designs? What about knowing how to program and set-up computer controlled milling centers and such?
Or does he see himself sitting at a computer doing nothing but AutoCAD?
I'd check out the work sites before investing any time or money in 'training programs.' The employers know who they hire and where they get their best employees.
Good luck and tell him hi. By the way, I give the same advice to college-bound students - just because some school offers a degree doesn't always mean the employers have historically found the graduates to be useful employees ready to hit the ground running.
John