After a frustrating couple of hours of "coding and not marking", I went out on my bike for 30 minutes to blow out the cobwebs. However, crossing the park I was stopped in my tracks when I saw this self-propelled line-painter. It makes sense that they exist as, when I talked to the guy supervising it, they save hours of work. With football and rugby pitches, they have to be set up to coordinate with the positions of the posts, or some embarrassing mistakes can be made! The biggest time-saver is the marking out of grass running tracks that used to take 2-3 people more than a day, but now can be done in 90 minutes!