I installed a quick mount license plate holder on my Tesla Model Y and it has a key to secure it to the vehicle. I wanted a cover to prevent road dirt and grime from getting into the hole.
This should also work for many other items that use this size key.
I tried a few different sizes and got it adjusted to fit my lock snug without risking it breaking while being removed.
I recommend printing in PETG or TPU with 100% infill. It only takes a few minutes to print.
It's a very small part and may require a little trimming if your printer isn't perfect.
Mine had a small blob that I easily removed with a knife.
You may also need to scale it slightly to suit your printer and lock.
The author marked this model as their own original creation.