Anyone seriously into postcard collecting (deltiology) would probably know of the Alfred Mainzer company’s Mainzer Cats postcards that were produced from the 1940s to 1960s. They depicted colorful and kinetic scenes from everyday life and activities such as sports back in the day, except the humans were replaced by anthropomorphic cats. The artist was Eugen Hartung (1897-1973), and he rendered them in a very vibrant, fun and therefore memorable style. They are so detailed that one can study them many times and still discover new delights.
The Mainzer company imported the cards from Switzerland and at first bore the Max Kunzli name and not the Mainzer imprint. Later on the Mainzer brand was visible as well when Mainzer purchased the plates from Kunzli. As their popularity grew, there were many series also printed in Belgium, Spain, Turkey and the United States. Most of the cards are still very collectible today, and the prices are certainly not outrageous, usually between $4 to $40. Most are around $10 plus.
Your best bet would be to hunt them down on ebay and Etsy If you want a guide, there is a book available.
Les Chats d’Alfred Mainzer (Paperback)
There is also this French book which title means The Cats Of Alfred Mainzer that provides 184 images from the original postcards. Mainzer has not given a definitive answer but it seems they published roughly 200 different designs throughout it’s lifetime. It doesn’t matter if you don’t understand French, this book is a great resource. $20, available on Amazon.
Delightfully Dressed Cats Postcard Box Set
There is also a 2018 released set of 36 postcards (modern reprints) on a larger sized, heavier card stock complete with a really nice box from Laughing Elephant. Though not the actual vintage cards, these are highly sought after as well and currently out-of-stock on Amazon. Check it out here.
In researching this article I was surprised to discover that deltiology (collecting of postcards) is the 3rd largest collecting hobby worldwide behind philately (stamp collecting) and numismatics (coin/banknote collecting). Check out these sites and articles for more interesting reading on how the hobby evolved throughout the decades and more detailed info on the Mainzer Cats.
https://en.wikipedia.org/wiki/Deltiology
https://aboutcards.blogspot.com/2012/09/mainzer-cat-postcards-and-eugen-hartung.html
https://yourhub.denverpost.com/blog/2020/01/cat-lovers-whimsical-sports-mainzer-postcards/257798/
