It all depends on the child!!!!! A nine year old can have the motor skills required to use rotary cutters, but may or maynot be responsible enough to respect the safety/dangers that go with the use of this tool. I have taught my autistic GD to quilt. We started when she was about eight. We took it step by step with a lot of safety instructions along the way. Because she was very accepting of safety issues there have never been issues. In fact it made me more aware of practicing safety. You know -- Lead by example.