The key clips in and you can magnetically stick it to a discrete place on your car. I'm using it to hide my key during runs.Disclaimer: as pointed out in the comments, if a thief finds your key, you will not be able to claim any insurance money, so be careful!
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Imported from Thingiverse: https://www.thingiverse.com/thing:1908
Original creator: InnovationByLayers