Any machine that will actually sew will probably pierce her finger if she puts it in the wrong place!!
If you explain to her how it works, and that the machine doesn't know the difference between fabric and fingers, she should be able to sew with supervision until you are sure that she understands what can happen if she's not careful.
The same with the iron. Help her understand that if she touches part of it, she will get burned but that the handle is safe and isn't hot.
We need to teach our children to respect the world they live in.
Mary Kay posted this recently on FaceBook, and it is so true!
"Prepare the child for the path, not the path for the child."