You would think this would be a dangerous activity but it turns out to be petty tame. About 1/20 kids burns a finger, and when they finish yelling they inevitably tough up and get back to work because they are having so much fun.
So anyway, scrounge up plumbing torch and some nails and let the kids make "mini-swords." You can use a sledge hammer or any big chunk of metal as your anvil.
If you want to see what the "swords" look like my kid has pictures on his site: https://lemonsword.com/