Magnetic Key Holders
 

Once again I find my spare key and my magnetic key holder missing. Last time I bought one that said it had an extra strong magnet and would not vibrate off. Obviously that is not true.

Is there a place to buy one with a magnet powerful enough to hold it to the car? If so, I cannot find it. I did find a YouTube video that shows how to make one yourself, but I don't have the tools.

I would call NASA.
They have big and strong everythings.

How many of your keys are scattered about town?

I'll ask my neighbor which one he uses -- that vehicle goes everywhere

Car Key Holder that does not vibrate off
 

Violet, I'd suggest trying to find a "rare earth" magnet. THOSE things are the strongest magnets in the world. I personally have seen one about the size of a dime pick up 20 pounds. They're probably expensive, but I'm sure one of them would hold a hidden key box on the car.

Rare Earth Magnet
 

Thanks so much. I will look for one.

Also, depending on where you put the box, you might need to clean the metal for the magnets to get a better purchase. Rust, grime, and dirt will all mess with magnets.

The YouTube video I saw shows a flat, circular magnet with a loop on top. Man got a plastic vitamin bottle with a screw off lid, heated the tip of a screwdriver with a torch, pushed it through the lid of the bottle to make an opening that the U shaped loop on top of the magnet would fit through, hooked key to loop, key inside bottle, screwed on lid and stuck it up under the car. I don 't have the tools to make one of those so I have a different problem. I plan to add the rare earth magnet, which I have ordered on Amazon.com, to a plastic key box. Now I have to determine what kind of glue holds such a magnet to plastic reliably and buy some.

You don't need a torch to do that, Violet. A simple disposable cigarette lighter will do the same thing to a screwdriver. To make it even easier, you could probably drop the bottle cap into a cup of boiling water to help soften it. I don't know about gluing anything like that.

Bonding dissimilar materials can be an adventure.
We all know that from having the front of refrigerator magnets fall off.

I think cyanoacrylate based glue (read ---superglue) is a logical first place to start.
If you can find out what type of plastic it is (sometimes it will be marked "ABS" etc), we might be able to find some really expensive specialty glue.

2 part Epoxy has been known to work in such situations (metal to plastic). Just use it w fresh air and have your toothpicks ready for striiring and your pieces ready for gluing.

I understand the novelty of a weatherproof water bottle dangling from the vehicle, but sure seems it would make a racket