My 9 year old son has shown interest in learning how to sew. I have an old machine for him to learn on and he knows this. He has picked out some precut fabric that he wants to work with. The question that I have is how young would you allow them to use the rotary cutter and rulers? In case he needs to cut some strips for the quilt top. It just makes me nervous to have either of my kids around that or would a plain scissors work the best?