They were banned in schools in the 1970s after parents complained they were used as weapons and caused serious head injuries. Their history is here from the first Hopalong Cassidy box, to the the last of Rambo Sylvester Stallone model.
I had a red Stewart plaid one in third grade that I remember, complete with a thermos. There were no ice packs included, ever.
The Antique Trader attributes the popularity of metal lunchboxes to television.
Take a tour of the museum with this YouTube video if you can’t get to Columbus Georgia.
Mr Woodall has written an encyclopedia shown below