You might want to explore Junior Colleges in your area. Many JC's, but not all, have vocational training in addition to academic training. Agriculture departments often offer vocational training (i.e. mechanics, engineering, welding, fabrication, and special math classes that are geared toward these vocational fields) as well. JC's, unlike specialized Vo-Tech schools, are geared to part time adult students.
I can't speak for all Vo-Tech schools, but some offer evening extension classes for folks like you and me that do not want a degree or a trade career. The instructors are usually practicing trades people who have day jobs and only teach part time. I attended one Vo-Tech for about 6 semesters and took some really helpful and interesting classes in welding and body work. They were geared to part-timers, were very hands on, and the instructors expected you to have your own projects to work on. I was able to complete a project vehicle and learn a lot in 6 short semesters, @ 1 evening a week. Best money I ever spent.