Corvette tech ou quelque chose comme ça ? C'est un ancien mécanicien de Grand-AM / ALMS / IMSA qui travaillait chez Magnus Racing qui a parti ça !
Works really well with some string, just needs to be thin string of contrasting color to the ruler you use and it's super easy to read. Often what people do is they get a fishing rod reel (fishing rod without the rod) with the correct string, makes it easy to store the string later and also acts as a weight to keep the string tensionned between the front and rear alignment bars.
In DTM we use the same method with strings for setting toe, camber gauge for camber and ride heights were done with a construction laser (like a home depot laser) set to a reference height to the corner scales, then you just read the height off a reference point with a ruler / vernier.
It's probably easier to do the alignment with a machine (I've never done it personnaly) but I've never been dissapointed by doing it myself. I had a track car that I always did the alignment myself on, you could let go of the steering wheel at 180 and it would stay straight.