This holds a spare key outside our camper…..just in case we get locked out or have unexpected guests.  

I added a couple of unique design features that worked best in my application.   First you'll notice there is no bottom to the case. This not only simplifies the design, it allows for water and moisture to escape the holder,  keeping the key dry.  

I used neodymium magnets (available everywhere) which are incredibly strong so there is no worry about losing the holder when on bumpy roads.

I included the step file so you can modify the design to fit your needs.

The holder was printed in silver ASA so it nearly matches the color of my RV making it a little more difficult for wandering eyes to spot.