A QR Code That Returns Your Keys

Have you ever lost your keys on the train or the street and had to give them up for lost? Some stores have keyfobs with a barcode connected to your store account, so the keys can be turned in at any of those chain stores, and the store will contact you or even send you the keys!

But what if that chain is no longer around, or you’re on vacation in another state and they don’t have the chain store there? Then what? This QR code keychain design will allow someone with a smartphone to take a picture of the fob and automatically send you a text that they found your keys, with their phone number so you can call them and arrange to get your keys back!

QR Code Keychain. Photo has been altered to protect the phone number encoded on the fob.

The code can be generated any number of places or you can have fun with URI schemes yourself. Much like the mailto protocol, sms format is


Once the code was generated, I etched the acrylic on our laser cutter, going over the etching twice for extra depth, and filled the recessed areas with polymer clay [you can use fimo, sculpey, etc.], put it in the oven to set and covered with a clear layer of nail polish for added protection.

Share this!

25 thoughts on “A QR Code That Returns Your Keys

  1. Great work with the clay in the recessed area idea..
    One question, have you had any trouble with the keyring-attachment-loop in the corner snapping off?

  2. You might also be able to do this by printing out the QR on some shrinky-dink paper and punching a hole in the corner before you bake it. it’d be more accessible than the laser technique.

  3. NICE work. Combines software, design chops and using -cutting edge- tools. There was a service category called “Return Labels” but that whole category suffered from overambitious managers etc. Perhaps the DIY approach has a new intermediary?

    Hackerspaces producing an etched QR to a Permalink that secured logins would be sold to as a fundraiser. Replicating the DAV keychains but way lower risks.

  4. to david: i haven’t put it through anything like a rigorous stress test, but from my experience with acrylic, it’ll take a beating as long as you use common sense. just don’t take a hammer to it or sit on it (that would hurt you AND break it).

    to john: yeah, that could work, but in my experience of shrinky dink plastic, the image could easily warp or blur in the shrinking process, leading to corruption of the information. by all means, test it out, but don’t be surprised if it isn’t as simple as you thought.

    to oren: AWESOME idea! we could even add our hackerspace logos into the graphic.

  5. I’d kill to do something like this, but alas, I have no access to anything that I could (physically) create the tag itself.

  6. and putting only the cell number on the tag , you’re also ok from the security perspective 🙂
    I think that attach a qr with your address to your keychain maybe welcomed as a blessing from a wannabe burglar

  7. Laser engrave on white acrylic through the protective mask that comes on the acrylic. Spray paint black with Krylon Fusion. “weed” the mask. Spray surface with coat of clear acrylic for protection. Voila!

  8. greg: though engraving through the protective paper probably wouldn’t work well [it has been my experience that the latex underneath would stick the burnt paper to the acrylic]. another line programmed to be only a slight cut would probably do the job. then one could peel the squares off and go on as you suggested. cool idea!

  9. I love how professional it looks! I have a laser cutter, but I’ve never heard of this “filling with clay” business. How do you get the clay into just the recessed areas? Is that a tedious process, or is it more a matter of squishing some clay onto the whole fob and then squeegeeing off the excess? I’d love to hear more about that part. Thanks!

  10. chris: the technique was basically what you described. push as much of the clay into the recesses as possible, then take a firm blade and cut off the excess. “squeegeeing” would really just pull out the clay you stuffed in, so just, carefully, cut off the excess. it’s a little delicate, but the result is worth it, as you can see.

  11. Here’s an even better idea: write your phone number on a piece of paper and… done. Everyone can read it and call / text you, even without knowing what those codes are for or having to run an app. Brilliant!

  12. You can go to any major pet store, and get them to make you an engraved pet tag in many shapes, for < 5$… Put your phone number on that, and you won't be depending on someone to know what the heck a QR code is… This is cool and geeky, but I'd bet reduces your chances of getting your keys back to 25% of what just a tag with your phone number on it.

  13. It asks for sending the sms, any way to script it so it sends it automatically? Cause after seeing that it´s gona send it people can alter the message or evena cancel it if they want to.

Comments are closed.