I never could bring myself to cut holes in door panels for anything especially speakers. Recently, I had to trim out new door panels for armrest screws and window cranks. Larger holes aren’t bad to cut but the smaller ones a bit more challenging.
Rather than chase down leather tools I came up with an affordable alternative that worked out really well. I discovered that using sockets the same diameter as the desired cut and pushing them from the backside out would create a bulge in the material. Then, using a razor blade, a careful quick trim and done. Perfect cuts.