Up for bid on eBay is this set of 400 vintage long-word flash cards.
The seller says, "These are a very early set, and may have been hand made. Nearly every card has a penciled line so that the words would be straight. Made of a medium weight paper. These were found in a teacher's estate and many of the other items were dated the late 1930s and early 1940s."
To own the flashcards, click the link provided.