In 1966 Marvel Comics published a series of "Mini-Books." They measured ⅝" by ⅞" (smaller than a standard-sized US postage stamp!) and were sold exclusively in 10-cent capsule toy vending machines across the United States.
A total of six titles were issued, each of which featured a different Marvel superhero (the Amazing Spider-Man, the Incredible Hulk, the Mighty Thor, Captain America, Sergeant Nick Fury, and Millie the Model) in 50 pages with minimal narration and art.
The Mini-Book pages are smaller than a U.S. postage stamp
This month, Abrams ComicArts is releasing the Marvel Comics Mini-Books box set. It includes hardcover facsimile editions (enlarged to 4.25" by 7.25") of all six Mini-Books plus a seventh book with Mark Evanier's delightful "mini-history" of these mini-books. Unfortunately, the books weren't reproduced as exact duplicates of the original mini-books (although the seventh book reproduces the actual size pages as shown in the photo above).
Capsule toy vending machines can still be found in the US but are nowhere near as prevalent today as they were in the 1960s. However, in Japan, capsule vending machines are ubiquitous and are filled with amazing collectible toys — scale models of human organs, replicas of vintage photography equipment, sumo wrestlers, sushi, and tiny eyeglasses. The last time I was in Japan I took photos of one of the many stores that contained hundreds of capsule vending machines. They're called gashapon, which is onomatopoeia for the sound of the crank makes when you turn it ("gasha") and the sound when the plastic capsule drops onto the tray ("pon").
A gashapon store I visited in Kyoto, Japan in 2018
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