Went to see beautiful film on Thursday, "Into Great Silence", about the Grand Chartreuse Monastery in the French Alps. Imagine my surprise when the monks were eating from 3 tier or 4 tier stainless steel tiffin boxes in their cells and out in the garden etc :-)
it used to be every working stiff's accessory in France (and elsewhere i guess). Take-away lunch, multiples tiers, and often insulated. I used to sort of collect them in flea markets. threw everything away. DUH!