I have seen people use the egg cartons but they took the the lent from the clothes dryer and used that. With wax and if you get the cardboard egg cartons you just cut them I little sectionsI love topics like this. Not only historically interesting, but fun and practical too. Might be fun to put together a kit like that sometime.
I've been testing out a variety of different fire starters for the emergency kits. Made quite a few Vaseline coated cotton balls, which work really well for starting fires, even when it's damp/wet - though I haven't tested igniting them with a flint yet. I've also made little wax/cotton cubes in an ice tray - took some cotton balls, stuffed them in each cavity, added a small wick to make them easy to light (I usually get my wax by buying cheap candles at the dollar store, then save the wicks for stuff like this. Pour hot wax over the cotton and when it's done you have a nice little fire starter that burns really well. Another one is to take an egg carton and put some sticks, tinder, etc. in each cavity, and again, pour hot wax over it all. Cut them into individual fire starters. Also works well.