Introduction: Hidden Spare Car Key for Emergencies
This is a sure fire way to insure you will always have an emergency spare on your car. I never liked the design of those magnetic spare key holders, seems like snow and icy conditions could knock it off, and a thief could spot that in a heart beat. *Edited Note- So many people have commented on ways to hide a Rfid key that its worth checking out the comments below. This is what I love about the Instructables community, everybody pitches in to help refine ideas. I will edit this again to include the communities ideas and mention the users names to give them credit. Thanks a bunch!
Step 1: Materials
Gaffers tape is about the the toughest, stickiest tape I have ever found, if you haven't tried it get a roll. I've had a six inch strip stuck the road in front of my shop for months, snow rain and street sweepers have not taken it up yet. You'll also need a can of automotive undercoating, and some scissors... and of course your spare.
Step 2: Pick a Place You Will Remember!
This trick will make it hard to spot the key, so make sure you remember where you put it. I put mine right under the lock on my driver side door, since nobody will ever see it and that's the easiest place for me to reach should I get locked out.
Step 3: Cut Out Some Tape and Attach the Key
Clean the chassis or other surface you choose and let it dry. I just wiped mine down, since its so rusty anyways. You can rip gaffers tape off, but I went a head and cut it nice and straight to help disguise it. Stick the key in the middle of the tape. I used two pieces slightly over lapped since my Toyota has a wide key. You might be able to get away with one strip. When its cut out stick it on the underside of your car on the spot you have picked out.
Step 4: Cover It With Undercoating.
Undercoating is sprayed on the underside of most cars, its a rust deterrent and sound deadening material. I will coat more of my underside later (which I really need lol) I only did the area where the key is for this tutorial. Undercoating is a very thick gloppy substance and as such deforms the shapes it is sprayed over, this helps disguise the shape of the key! In the first pic you can probably make out the shape of the key if you look hard enough. if I wait a couple of days I can reapply and that shape will disappear completely. Also as road grime and mud etc builds up the key will be further obscured. The best part is the key is now entombed in a water proof sealed container and when I dig it out it will be good as new. The undercoating never truly "cures" so you will be able to dig into it with your finger nails or a small knife even years down the road. Hope this helps someone one day! Thanks for looking.

Runner Up in the
Safe and Secure Challenge
67 Comments
4 years ago on Step 4
Thanks. Great idea. Though, I think I will add another smaller piece of tape to encapsulate the key. This ensures that the rusting metal or other metal does not chemically/electrically reacts and degrades the key. I seem to remember that different metals when exposed to water and salt (I live in a snowmelt zone) react and accelerate rust.
4 years ago on Step 4
thanks for this idea! I have two keys to unlock/start my truck so I've been looking for alternatives to a blatantly obvious hide-a-key.
Reply 4 years ago
Cool! Thanks for the comment. If you will, come back and click the "I made it" button and post pics if you have them.
4 years ago
Thanks for sharing your idea. I think it is great. I think your idea would be especially helpful for teen drivers too.
After reading this I had a small light bulb moment. I have saved old gift cards, plastic coupon cards and those plastic ad cards sent by a certain cable company. Some are thin enough so that two could be stacked. Cut out a hole the size of a flat key then place it on the other card. Tape them together with a thin transparent tape. Then tape it to a hiding place with the key in the cutout with the uncut card against the gaffer's tape. The key would be camouflaged so maybe it would be overlooked by a thief.
Any suggestions now on where the best place to hide the key for someone who is disabled and needs easy access to the key?
Reply 4 years ago
They make a hitch receiver safe.
Reply 4 years ago
The only place I can think of where you would't need to get down on the ground to retrieve it would be the wheel arch or on the inside of a bumper.
Reply 4 years ago
Thank you for the suggestions. It's not very easy to get to the inside of the bumper on my van. The wheel arch is just to messy for me. : ) I'm thinking about the roof. It is high enough that most people don't notice it. I just need to get some of the gaffer's tape to hide the key. I've even think I might place two or three fake ones on there as a diversion.
Reply 4 years ago
Thank you for the hitch safe suggestion. I didn't know about those. Unfortunately my vehicle does not have a hitch and I can't spare the money to install one right now. I will keep it mind. : )
Reply 4 years ago
Genius! I like reusing stuff so that is a great idea for those cards. Some people are suggesting behind the license plate. Most those folks are in Europe, so that's where to look if you are on the run in Europe and want to steal a car, lol. I must emphasis after a second coat of undercoating you really can't make out the shape of the key, but its still a great idea using the cards. Thanks for the comment.
Reply 4 years ago
I don't want to put behind the license plate either. I was considering using the cards someplace that would hide the key without using the undercoating. I would never be able to reach under the car to retrieve it. I will have figure out a good hiding place I can reach without bending too much. : )
Question 4 years ago
Key FOBS are large compared to the old metal keys. How do or would you hide a newer key FOB. It is bulky and expensive to replace.
Reply 4 years ago
There are answers to this in the comments, as I understand you get the key part cut which will unlock the door but not start the engine, then you hide a fob key in the glove box. Yes they are expensive, but may be cheaper than having your car unlocked by a lock smith. Thanks for looking.
4 years ago
Where do find a car that still uses a flat metal key? Most cars now have a fob you just put in one's pocket or purse.
Reply 4 years ago
Valet keys are copies without the fob. A duplicate can be gotten at most places that sell keys. (For any car)
4 years ago
Rather than just wiping it down, you may want to take a wire wheel to that rust. Otherwise the surface is less than ideal to affix tape to (in other words, it'll pull away and fall off). Tape is only as good as the surface you stick it to. You may want to undercoat the rest of that chassis while you're under there. heh heh.
4 years ago on Step 3
I hide a key also but mainly for lockout. There are a number of places you can hide a key if you have a screwdriver, which you can normally borrow. Your idea is good for no tool access.
What prompts me to comment is if you have a key with a chip I have found you can get a key cut without the chip that will open the door but not start the car for fairly cheap. This is good if your in the middle of nowhere throw your hoodie in the car forgetting the keys are in the pocket.
Tip 4 years ago
For those who may not know, gaffer tape is used by sound and lighting technicians to keep microphone and electrical cords in place on stages or other performance venues. It is available at most stores that sell musical instruments and also those who sell amplifiers, PA systems and such. It ain't cheap, but it's really good stuff for many uses and, as the author of this project states, it sticks VERY well to nearly any surface.
Reply 4 years ago
Very cool - sounds like it would work much better than your standard fair duct tape, I might have to get some! Looks like you can find it on Amazon too: https://amzn.to/2Gu9JM0
Reply 4 years ago
I think I remember that gaffer'st tape is not only strong but leaves no residue on surfaces it's applied to. Any other tape that leaves a residue on the key could interfere with the internal mechanism of the lock. Is this correct?
Reply 4 years ago
Yes, absolutely correct. Duct tape is especially bad about leaving residue and about the only thing that will remove it is lacquer thinner or mineral spirits. Not something you'd probably have ready access to it you were using and emergency key.