I've had a daily carry since I was nine, got "my" first knife when I was 8. It was an old metal handled case jack knife that had been my grandpa's. As far as I know minors can't legally buy knives wihthout the consent of a parent. After that its legal to carry so long as its a legal knife, and your not using it in a threatening or destructive manner.Thats from my experience here in ohio though. I don't think there are alot of laws regarding knives yet other than the usual concealed weapons stuff concerning things like gravity knives and switch blades. Things may be diferent in less knife friendly states or countries.
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Fix it right the first time, use Baling Wire !