/diy/ - Do It Yourself

I mean this style that goes under cars.
The way it works is, it logs its location via GPS, every <insert time interval here> and stores that data on a hard drive.
After you retrieve the device and plug the hard drive in the computer you get the list of all locations logged.
The entire device is in a plastic box, that connects to the undersize of a car via strong magnet.
Can you make one yourself?