Toys that gave children the opportunity to maim themselves or their friends have sadly disappeared.
I remember 'experimenting' with Jetex motors - what could possibly go wrong.
I also have a photograph of my brother with a stream of water about six inches from his ear as he dodged one of those water rockets that took off at about 600 mph and reached some serious altitudes. The stream of water was all the photographer (me) captured, the rocket was long gone.
Tree climbing. I take the grandkids go to a place where they can climb a climbing wall, protected with a rope and harness and they have a great time, which is fine, but also very organised and a bit sterile. We just climbed trees. I have another picture of my brother about 40' high in the thinning branches of a tree, the branches a baboon might go to in order to avoid being eaten by a leopard. My grandad took that picture and was completely unconcerned.
Someone already mentioned air gun fights. We used to wear an anorak for protection, but that didn't work for a pellet to the knee - ask me how I know! I still have the scar more than fifty years later.
Anyone else make bolt bombs? A friend at school managed to blow his hand up with one, a nasty injury and he lost part of his index finger. Nobody got sued or went to prison and he was a celebrity for about a week.
Sometimes I wonder how we survived.