A money making exercise, hmmmm. True, I attend a lot of craft fairs but this started out as a hobby (still is) and the wife pointed out that since I could only use one pen at a time and I had about twenty what was the point in making any more. In fact it was all her fault anyway, she used to run a jewellry business and kindly bought me a pen at a craft fair and I made the mistake after a few beers of saying that I could make it better, and with an angry retort about how ungrateful I was I had to shuffle off and book myself onto a woodturning course, and the rest is....
However, I chose to do this to generate a bit of extra income so that I can send my children to a school of my choice not the governments. I cannot see that anyone could actually make it their sole or main income, the effort required to generate the volume would be phenomenal.