I'm from NJ so basicly did enough research to understand the law... sorta. If you have a slingshot have a reason that is legal and explanable, some sellers see it as slingshots being outright banned but the law is not written like that. Still, I wouldn't want to get pulled over with a wrist braced frame in my car in NJ, a non braced frame or a natural fork would probably go over better with the 5-0.
Bear in mind you're not only dealing with state law, but also county AND municipal ordinances. Check them all to be sure about whether they can be used/carried at all where you live...and then check hunting regulations.
If the good Lord didn't want us making slingshots out of trees, he wouldn't have made trees out of slingshots.