We found these wonderful homemade "fish" flashcards when cleaning out items from a 1950's - 1960's estate.  There is a lot of 12, 1 side is coated with a "somewhat" wipe away surface.  You can see where they have been written on and wiped away there is still a small amount of black left on them.  There is a bit of edge wear on them and a few have been bent once (you see a crease but it's not permanent).  Overall these are very nice. 

Fish Flashcards Vintage