My granddaughters started sewing with an inexpensive Brother machine set up on their little- just their size- Care bear table & chairs when they were 4. I never heard of ( or thought about) a Needle guard. We never had any issues, the only thing I never let them do was touch the rotary cutters or iron. They could cut with scissors or bring me what they wanted cut. I never let them use the cutters until they reached 18. They started being allowed to iron at about 12