Bill sticking must be a pretty frustrating job.
No sooner have they finished pasting up the latest set of coloured paper squares than they have to scrape some off and start all over again.
Today’s invention is a robot printer for such advert spaces. Each large billboard would be fitted with a small printer suspended, in a weatherproof case, from a vertical arm. This would attached to a cart running on a track along the top edge of the billboard frame.
The printer would be equipped with a wireless receiver which would allow it to be driven by motors to precise locations (just like a flatbed printer turned through 90 deg into a vertical plane).
Fed with waterproof paint/ink from reservoirs behind the board, it would be capable of repainting a huge advert in minutes and thus providing a cost-effective alternative to the electronic adverts which are supposedly on the rise but which are enormously costly and unreliable.