Copy a Car Key With a 3D Printer





Introduction: Copy a Car Key With a 3D Printer

About: Smith|Allen is a design firm based in Oakland California. Our work is interdisciplinary in focus bringing design, innovation, and novel concepts to bear on a wide range of projects. Smith|Allen brings toge...

Disaster! My only copy of the my car key broke, I park on the street and have to move my car by Saturday 9AM today is Friday and I have to go to work. What to do? I could call an auto locksmith or take it in to the dealer but that would be expensive and take time. There has to be a better way, I'm going to upgrade my key into the 21st century and make a 3D printed copy with Fusion360.

Fusion360 is a powerful cloud enabled 3D modeling platform, and the best part if you register as an enthusiast it's free!

Step 1: What You Will Need

The process of duplicating the key is pretty straight forward, we will use calipers and a camera to get the general geometry of the key. We will then model it in Fusion360. And finally we will print the key on a Connex500.


1 Camera/phone

1 key to be duplicated


1 Object Connex500 or Shapeways

Step 2: Photograph the Key Orthagonally

The first step to making a reconstructed duplicate is to take orthogonal photos of the original. We need to get at lease one good shot of the side of the key and a basic shot of the profile of the key. These photos will be our guide for tracing and where to measure.

Lay the key down and get it as flat as you can. Try to get the light as even as you can. Take the photos from a bit further away than you think you would need to, taking them further away means the profile will appear 'flatter'. The flatter the image the more accurate the trace will be.

Open up a new design in Fusion360, in the model workspace go to the insert tab and add in your best photo of the profile.

Step 3: Model the Blank

Now that you have the photos for reference use your calipers to get a known easy to measure dimension. In this case I used the width of the key. With that dimension use the calibrate tool to scale the image so it is at the real scale of the object.

Now that the image is scaled we can start building the blank of the key. Use the calipers to measure the length and width of the key. Make a new sketch then a rectangle of the basic size of the key. Measure the keys thickest point and extrude the sketch to that volume. If you want you can also add a handle at this point.

Step 4: Model the Grooves

Next add in the grooves on the side of the key. Use the caliper to measure the distances both along the axis of the key and along the width of the gaps. Record them in a new 2D sketch.

Use your calipers to get the depth of the grooves. Extrude them down but do not subtract them yet.

The key I'm using has the same grooves on both sides, so copy the bodies you just made for the grooves and then rotate them around the center of the key, you should now have the same volumes on the top and the bottom.

Use the combine tool and the action of 'cut' to carve the tool volumes for the grooves.

Add chamfers at the end of the grooves to add additional strength.

Step 5: Model the Profile

Now that you have essential the exact same thing you would cut a key from with a machine it's time to cut the profile. The profile of the key is what does the work of moving the lock pins to the unlock position. You can see how they work in the gif above.

Turn the image of the key back on. Make a new sketch of the profile of the key. Zoom in and trace the key as carefully as you can. Accuracy is 'key' here.

Once you have the profile make a box around it to close the profile. Extrude that profile up to cut your blank.

Step 6: Finalize the Model

Add some finishing touches to your model, you could add some fillets to the handle or refine the profiles.

When you are ready use the combine tool again to join the blank and the handle.

Right click the new body and 'select save as STL'

Save the stl out to the location you want to print from.

Step 7: 3d Print the Key

Once you have the STL model it's time to move over to the printer.

You need a high resolution printer to do this, you also need durable material. You might be able to get away with using a Form1 or Ember printer, there are many resins out there but you need one with high strength since the part is small.

We used the Connex500 at the piece and the Endur polypropylene-like material. Although nowhere near as strong as metal it should be good for a couple uses.

Step 8: Test, Reprint, Test

The moment of truth. Try the key is a non-essential lock first, that way if it breaks off it's not too big of a problem. Go slow and jiggle the key if necessary.

If the lock makes marks on the key or doesn't fit then just go back and reprint.

Good luck!

Step 9: Make It Work!

Finally go big! You can see here I just went for it, and it worked...sort of. The key fit the lock and was able to turn, it broke when turning the additional bit to start. With the key engaged you can turn the ignition with a screwdriver (you may be able to do that without the key too).

Success (sort of) I was able to avoid a ticket and get through the weekend!

In a sense its also an epic fail, but so close, with a little bit more material innovation 3D printing a key will be a reality!

It does raise a lot of questions, how much stronger does the plastic need to be?

What would a fully 3D printed lock/key set look like?

Could metal be integrated into the plastic print to make it work better?

Could it work printer from steel?

Up next how to replace your ignition lock cylinder...



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    21 Discussions

    Now that I have the photos of your keys....hmm....

    Maybe bend a small loop in thin but stiff wire, heat it and insert it into the plastic. Let it cool around the loop and pull it out?

    Another idea would be to de-couple the two motions of 1)bumping the pins and 2)turning the cylinder.

    Make the key out of plastic, but leave a notch near the 'handle' end so you can turn the cylinder with the screwdriver, but still have enough material to pull the plastic out of the keyhole.

    For a more durable permanent replacement you could find a way to cast a metal copy. I'm sure in some cases that could be done straight from the original broken key, but if it's too messed up the 3D printing trick might be very helpful.

    Hey, awesome use of a 3D printer!

    Just wondering... In most modern cars they have an immobilizer RFID tag in the key, so if someone makes a fake key the car still wont start. How did you start your car without it?

    3 replies

    If someone needed to do this to an RFID enabled key they could just keep the remains of the original key nearby when they use it. Put them on the same keychain or something.

    my car is not what you might call 'modern' this would not work for new cars. But there are many other locks out there that could use 3d printed keys!

    I was also thinking about this. My mother's car key broke and we placed the rfid near the sensor and welded the remaining of the key to a washer. I've heard it's quite expensive to make copies of those keys.

    You Could possibly consider using some carbon infused plastic for better strength, or you could drill some holes through the key and fill in the holes with some stiff metal wire coated with an epoxy.. awesome instructable, i had fun reading it

    I love the idea, but I agree, it needs a little more work shopping :). Broken keys in the lock are a hassle in and of themselves! I'll be excited to see future prototypes!

    1 reply

    One could make the model with a hole for a small screw, say a M1.4 or whatever will fit in the width of the key, and then get a piece of threaded rod or a long screw and thread it in. I find that if you leave a hole in a 3D printed part at the size of the tap diameter then metal threads will cut in nicely. It might not keep the key from breaking, but it would probably give you a better chance of pulling it out if it did.

    That's pretty cool but be careful with newer car keys since they have sensors in the key. If you drive off without the correct, programmed key, it'll just stall out on you. That key doesn't look like it has one so it's still a pretty cool way to make a custom key!

    1 reply

    not a problem on this car, but who says it needs to be car keys, you could 3d print a key to another lock as well!

    you could also print the basic profile, and have a conventional key cut from that.

    1 reply

    great idea! I forgot to mention that in the post but that was the original idea for how to make it permanint, just need to find a person with a key cutter who is willting to try.

    You could also use the file to print a wax key with a cnc mill and use lost wax casting if you don't want it to snap off.

    Really cool. But now I have a picture of your key, where's your car parked atm? >:D

    Haha, glad you got the car moved. Seemed to go as expected but nice Instructable!

    This is so cool!!! maybe you could get a cnc machine to carve it from metal or something

    Having a metal pole inside the key shaft with a cap on the end would prevent pieces of the key getting stuck in the lock if the plastic part breaks. If it does break, just pull it straight out and the whole thing should come out.