Here's how I like to engrave metal with a Dremel rotary tool. You can use whatever rotary tool you'd like, a Foredom, a Dremel 3000, a Dremel 4000, I'm using
Grinding with Dremel 3000
Dremel 290-02 Corded Engraver Kit
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Hanro Studios Dremel Engraving Tips and Tricks
Metal working: Making Dremelathe small rotary tool powered lathe
How I engrave my challenge locks