John in NM
I've certainly been sorry that I brought up stuff that I did over the years, but I figure I tend to remember it longer than anyone reading it, so why worry

The trick with the hobby-niche-$$$ equation is to luck into something unique or difficult enough that no one else is doing much with it, but there is enough demand and a way to reach those who will do the demanding. I've stumbled upon one of these all of once in my 41 years, my dad went looking for many and never found one. The internet helps a lot by the way, I think that was dad's problem, not lack of ideas, lack of such easy free publicity.

So I'd encourage you to make one, I'm guessing you know a watch forum or two

The thing that helped me out is that my product is considered cheap even compared to guys using cnc's to make similar things. I'm lucky to know a trick or two they don't (but most of you guys would ), but also I'm not trying to pay any rent with the stuff I sell. For me it's fun and a little extra spending money, that's all. I honestly don't know if I'm making $5/hour or $20/hour, I don't keep track.

So make a couple, price them to sell, and see if it was worth it to you. You can always stop making them if it's too much bother for the $$$