I´m going to keep this short. Whilst watching a football match tonight here in Mexico i noticed an ingenious, yet simple, approach the referees use here to ensure defending players are 10 yards away from the ball (free-kick). Referees have a pouch full of white sand/chalk that they throw to the ground at the 10 yard mark. The referee can use this marker to penalize encroachment and help them be a better referee. It takes the referees here no more than 2 secs to throw it to the floor, and in no way interrupts the game
Premier League take note, technology is not just computers. Technology is defined as something that overcomes an issue and makes things better, and in this case the technology is sand. Big issues in the game with technology, but little steps will help us get to where the game has to be.
I also found an article to discuss vanishing spray, check it out here.
I like the idea of ´marching powder´.