Iflscience:
Thermite is conventionally used for heavy industrial processes like welding together train tracks. This guy, however, used it to create a homemade, super hot, metal-launching cannon.

Youtuber Colin Furze created his thermite cannon in his own workshop. You might already be familiar with Colin, who appears to be hell-bent on fulfilling the “mad scientist” stereotype. His past videos include him creating Wolverine-style claws and magnetic shoes to walk on ceilings.

Along with designing and building the launcher himself, another challenge was creating the thermite shells. Colin needed to get special permission as it's illegal to create something that can launch thermite – understandably. But he simply made the pyrotechnic cocktail by mixing iron oxide and aluminium powder. When this concoction is ignited it can burn up to 2,500 degrees Celsius (4,500 degrees Fahrenheit). But, a lighter or a match won’t do the trick to get the ignition going. Instead, you need a strip of magnesium. All in all, it’s a tricky task to create something capable of launching ignited thermite in a (relatively) safe way.

You can see how he created the shells and launcher here and here.

And obviously, don’t try this at home, kids.