Funny, was just thinking about this the other day as my daughter is currently obsessed with rocks. Did some research and.. nah, I'll just buy polished rocks off the jungle store.
A long time ago I had a brief rock-hounding phase and found some cool rocks. Polished them on a friend's polishing setup. That was pretty fun. I'd rather get back into that vs tumbling.
IIRC the setup my friend had included a diamond wet saw and various polishing and grinding wheels. For instance I used some wax to stick a rock on the end of a stick and shaped it into a cabochon and, using the various polishing wheels, got it to shine.
A tumbler is just a bunch of rocks and polish bouncing around for a week and you never know what you'll get.
A long time ago I had a brief rock-hounding phase and found some cool rocks. Polished them on a friend's polishing setup. That was pretty fun. I'd rather get back into that vs tumbling.