I mark my kitchen tools using a scriber.
It's just a sharp stylus point made of some hard metal (tungsten carbide or similar) in a pencil-like holder. You use it like a pencil to etch lettering into metal, hard plastic, or glass (watch for chips though).
You can buy one at a hardware store or online for less than USD 10. Once you have one, you'll probably find all other kinds of things around the house that you want to mark. You can usually replace the point when it gets dull (though they last a long time). Just don't get it mixed up with your iPad stylus!