I have been looking into selling the kits for window tinting.
The 2 front windows are hardly worth doing within the law, can remember what percentage it is but the film is basically clear.
Another thing that you guys might be interested in is 'paint guard', It is a clear film that is precut with a plotter to your cars dimensions, it stops all paint chips from stones etc and stops people keying your car etc. tis' great for people who care about their car!
In the case of Turnkey Instruments, makers of the Tintman meter, they seem to be doing very nicely thank you for sales, as it seems to be the accepted UK standard device for Police Forces and the only one fully accepted by the Courts. Seems they also make Skid meters, brake testers (Brakesafe), environmental particle meters, G meters etc for vehicle and MoT applications, so they are a professional company working closely with the Police and Government Agencies.
Don't get me wrong , I wasn't trying to deride them , only use them as an example because they had been mentioned earlier