If these things had steel bodies, just think of the possibilities we would have by using magnetic backed graphics...
You could change it according to your mood, location, or function. However, I do know the magnetic sheeting is very expensive. We (the DoD FD) bought a 3' wide roll x length unknown, but it was about 12" in diameter, and it was around $3,000.00. Of course this was for the US government so it probably came from the same place that sells those gold plated toilet seats and hammers.
Pat, you gotta remember that the MIL is their own worst enemy when it comes to spending money. Years ago, I got a request to quote on a field lubricator -- that's a truck mounted skid assembly complete with grease & oil drums, pumps, air compressor, hose reels, and all the rest to make a portable lube station. When I started reading the specs, I realized that someone had snipped and pasted pieces of data from our catalog, and our competitor's catalogs, to build a composite universal spec. Their universal spec drove us crazy - lube delivery was quoted at different temperatures throughout the document, some delivery rates were quoted for the bare pump, and others for the pump, reel, hose, and dispenser tip. If they had shortened the whole thing to just what they wanted it to do instead of telling us how to do it, it would have been a lot easier. They do the same thing to many products.
Consider what could happen to a stepladder with MIL requirements: They would want a unique step spacing, they would want non-standard aluminum side rails, they would want MIL spec rivets, and they would want the supplier to destroy 4 of them in a series of performance tests - plus, the whole order might only be for 12 ladders.
It's a little better thee days - many of the old, multi page specs have been eliminated, and they just order from a GSA catalog.
The magnetic material you bought might have been a unique thickness, or a different formulation, or needed 12 different sets of paperwork.