It won't grow bone just so you know, it's only swelling/scar tissue, therefore you have to be constant with it. I recommend a hard object for your chin, like a perfume bottle. I won't recommend a hammer since it's dirty and you might get an infection if you bust your skin open slightly. Your hand is just as good, it just won't be as even. You can also try bs for your infras and zygos, with the same hard object, it will make you look better if you say your maxilla is flat. For your mandible, supras and ramus i suggest hitting softer, since you might fracture your jaw or arcade. There's also an important vein around the middle of your mandible, make sure not to hit that one. There are side effects to this, such as nerve damage, problems with your sight if you hit around the infras, although temporary and pain. You'll feel like you have a headache depending on where you hit. That's easy to counter with basic pain killers, but don't abuse them since some of them fuck up your liver. The last thing i'd recommend is a massage gun, it's the most even with bs. Your parents are your biggest enemies most of the time, they love you probably but they're too scared to think beyond the small risks. This dosen't mean you should hate them, but actually try to explain to them with valid arguments and studies. Go ascend brother! No matter what you do or what others call you for trying to change your apperance.