Here's another interesting one.
Tessina Subminiature 35mm spy camera
>The Tessina 35 is the smallestminiature camerawith standard 35 mm film ever built. It is even smaller than the compactMinox 35and can be worn on the wrist, just like a watch. The camera was patented by Austrian chemical engineer Dr. Rudolpj Steineck in Lugano (Switzerland) and was manufactured by Siegrist in Grenchen (Switzerland). The camera was introduced in 1957 and was distributed by Concava SA; Steineck's company in Lugano. It remained in production until 1996.https://www.cryptomuseum.com/covert/camera/tessina/index.htmhttps://petapixel.com/2016/10/05/tessina-vintage-mini-35mm-camera-can-wear-like-watch/https://youtu.be/4JSUpNdKQFg 