There are several threads in this forum about small lathes. Some people say they are useless, others have made some really nice lights with them. Most of the people who have made disparaging remarks about the mini lathes have not used them. Some have used one (often when starting out) and base their experience on that one lathe.
I've used the 7x12 Sieg lathe (sold by many companies under their own name) as well as two of the 7x10 models and a 9x20 model. I've also used a 12x36 lathe and a medium sized Logan. They are all equally capable within their work envelope. Mass is not as big an issue as you''d expect because the 7x10 works closer to the chuck than a 12x60 with a shorter lever to work against.
Every lathe needs adjustments when purchased new, and occasional adjustments thereafter. These are often missed by neophytes and are often the source of complaints. Tighten them up properly and use the right tooling and you will find that they are accurate enough. Only the very small (5 inch swing and under) lack the ability to cut threads.
I've turned many flashlights on the minilathe. The carriage only travels about 3/4 of the length of the bed so you have to plan your work on longer lights. I prefer 1 CR123A for pocket carry, so that was not an impediment.. The single cell flashlight below was made on a 7x12 from a 1.5 x 6 inch bar of aluminum. The bezel, head and tailcap are all threaded.
I've worked on larger lights before. The swing over the cross-slide limits the diameter that you can work on. Max swing over the cross slide is just 2-1/4 inches. That does not keep you from working on larger pieces like finning 3D heads which don't have to extend across the length of the bed.
This is a 2D Maglight in a 7x10 lathe. I was not working on that light, just showing how it fits on the lathe.
This is a 4D maglight head. I was setting up an adapter to use it with a hopped up 2AA minimag.
So in summary, go for a Sieg C3 (sold by little machine shop, grizzly, busy bee, etc) if you want a small machine that will do all the things that a big one will on a smaller scale. It works for aluminum, steel, plastic, etc. Available new for under $700.