Depends @anon19591382
In general, cotton or flannel are the best. If you search eBay they are sold in 500 and 1000 bags.
Personally, there is no way in hell I would cut them out by had with scissors. I clean properly and go through a lot of patches in one session when barrel is getting a proper clean. Cutting them out by hand is just not worth my time.
That said, I DIY patches these days, more details here (below), think you’ll find it exactly what you’re after: