hobby: an activity or interest pursued for pleasure or relaxation and not as a main occupation:
I expect that the two requirements of a hobby are that one enjoys the activity and that it is not required as a source of livelihood. The broad category of hobby machinists will cover many facets. Some of us take pleasure in rescuing old machines and bringing them back to life. Some like to pimp out machines. Some just like collecting machines. For many of us, the machines are a means to an end, supporting other hobbies like rebuilding cars or motorcycles. Some like to make pretty things. I am not an artist. I can't draw a straight line without a straight edge and any attempt to depict a life form looks more like the work of a first grader. Designing things with my CAD system or machining things feeds my creative side in a way that generates huge satisfaction.
Personally, I really like the enabling power of my machines. Knowing that I can rebuild or create something, many times more functional than the original give great satisfaction. To that end, I can cast , forge, weld, and machine metals and have created one of a kind items that could not be obtained by any other way save finding another person with similar talents and paying for the work.
I take on projects for friends and neighbors as well. Most usually offer to pay for services. My comment to them is "If I had to charge for this, you couldn't afford it. Pass the good deed on to the next person." That conveys the idea to them that the service is something of value and the gift should be respected as such. If the project requires some out-of-pocket expenditures, I would tell the recipient up front that there would be some costs. If the recipient is too thick headed to realize that they should compensate you for those expenditures, the next time they come around, I would just be too busy to help them out.
For some individuals, the hobby can turn into a vocation. I know of machinists that started out that way and now have thriving businesses. For me, a hobby becoming a business ceases to be a hobby. I may still get satisfaction out of doing the work but other aspects of running a business come to play. With a hobby project, I can set it aside if I wish to. When it's a business, that is not usually the case. For a hobby, although household budgets come into play, there is not usually a need to justify the expenditure of tools and equipment in terms of payback. I can buy something just because it's "cool".
