I took the Thompson direct course 4 or 5 years ago and I enjoyed it. It was more for a hobby than to become a gunsmith. I did learn a lot of interesting things. I’m a qualified to be a gunsmith – no way. Do I know more about guns, yes.
My one recommendation is to ask for the information on the course, and then ignore them for a few months. I think they sent me additional information 2 or 3 times, each with a lower price. At one point it became so cheap that I just had to say yes. I took the financing option, so it was only a few dollars a month, and it’s tax deductible.
My one comment is that all of the testing is online, and do not evaluate the practical exercises. For example I read the chapter on stock making, but didn’t pickup a chisel or touch any wood. I still got 100% on the module. They probably don’t have the resources or the desire to grade practical work, but in my mind that would make this certificate worth something.
I’ve never been to any of them, but the NRA website has a number of links to training institutes. Many of these offer specialized one week training sessions. This is the sort of thing that I can see doing as a vacation. There is also a company in the US (who’s name escapes me right now) who produces video tapes on individual guns. It shows detailed assembly disassembly and some customizations.