Almost all of the floppy disk storage gadgets I have seen sold are made out of plastic. But a collegue remarked that steel, which although it will shield the disks from magnetic radiation, can itself become magnitized and thereby damage the disks it stores. In my case, the disks are 5.25 inch, double sided, quad-denisty. I agree with the comment that steel could become magnetized and thus cause more harm in the long run. Your question raises another issue, though.
Plastic can accumulate a static electric charge.
But then I thought, if the discharge was strong enough it might create a localized electromagnetic field of sufficient strength to cause an error on very high density floppy disks. It isn't just rural nets that have those characteristics. Experts differ from novices in science, chess, and other fields that have been studied not only in having more information in permanent memory but also, and more significantly, in being able to process it efficiently. Among experts, for example, items of information are more thoroughly indexed and thus can be rapidly brought to conscious memory. The items, moreover, are elaborately associated or linked with one another.