Having recently been painting a logo on a steel roller blind, today’s invention is particularly appealing.
It is a simple gantry system that moves a lump of chalk backwards and forwards, as the door closes, so as to create dots whose locations can be computer controlled. This draws a detailed but temporary image on the door surface, just like a computer printer.
As the door is opened, this film of dusty dots can all be brushed off, ready for the next cycle.
In this way, ever-changing adverts, logos, -tweets even, can appear on otherwise bland industrial units…at least when the weather is dry.
(Image copyright Danny Gilbert)