in a nut shell, the way it works is it takes a signal from the "transponder" and reads it and says ok 0101010101 is car A, and 001001001001001 is car B.... reading this "code" it if you wanted to make your own, you would need a "source of radio ID not powerfull at all since you want it to have a really short range, a reciever (a loop of wire), and a way to plug this into your computer for reading the data and saying what car had what time, as for making it, i rly can't say much[]