Instructables has a super-easy project for creating a magnetic arrow key hook. When placed on a map (that's on a magnetic surface, of course), it points you to your parked car... that is, assuming you have the clarity to recall where you parked by the time you get home. We wish it was a bit more attractive, but there are loads of ways to customize it to fit your aesthetic. We might try using a simple magnet (perhaps like these) and leave off the whole hook thing. You could also forgo the Sculpey and simply hot glue a magnet to a little toy car or something - plenty of options.