Make a QR code for a link, some text, a Wi-Fi network, a contact card, an email or a phone number. It is made in your browser, so nothing you type is sent anywhere. Save it as an SVG (sharp at any size, good for printing and engraving) or a PNG.
What should it hold?
Look
Your QR code
Test the code with a phone before you print or engrave it, and keep a bold dark-on-light look so scanners can read it.