Shadow boards are a common in 5S. They are used to nudge users to return shared tools to their storage place and ease the visual and from a distance recognition if the needed tool is available on the board or elsewhere.
In aeronautical MRO, the equivalent cut out foam shadow board in drawers is one way to prevent the dreaded FOD in aircrafts. FOD or Foreign Object Debris definition is “Any alien substance or article that invades any component of an aircraft which causes or has potential to cause damage to aircraft, persons, or otherwise diminish safety”. The FODs I am thinking of in this article are items or residual debris left behind or forgotten after performing maintenance tasks. Those Objects or Debris may cause Foreign Object Damage of various gravity, the worst being the loss of the aircraft and human lives.
Examples of FODs can be seen here: https://www.ntsb.gov/safety/safety-alerts/Documents/SA_054.pdf
Many Objects may become FODs apart from tools: hardware, eyeglasses, personal items, keys, wipes, cloths or metal shavings.
In order to prevent hand tools to become FODs, for example being left behind an inside panel after a repair or one of the mandatory Checks (periodic MRO visits), foam cutouts are used as visual aids for the mechanics to confirm all tools have been placed back in their storage place. Any tool not in its place nor in the hands of the mechanic can be a potential FOD.
The solid and contrasted color used as background help to see the tool’s outline when it’s not in place, just as the regular shadow board does in industrial workshops. The “clean-as-you-go” principle asks for cleaning and checking after completion of a task, including of course the visual check of all tools put back in their foam cutouts.
Good practice for aircraft maintenance borrowed more of 5S than just the shadow board, in fact aircraft maintenance embraced 5S as a whole, for the sake of staff safety and the safety of the aircrafts and passengers. Indeed,cleaning of the aircraft and surrounding areas throughout the maintenance areas is common and enforced. I have been positively impressed with the 5S state of the first hangar I visited.
More sophisticated means are used to ensure tool control, like RFID tags, tool counters, etc. The visual aid of a shadow board or its variant remains one of many means, a cheap and convenient one. Such a mundane board can avoid a catastrophe, a very good reason to use it.