There are two basic types of clickers: mechanical, where when you operate the clicker some part of it moves and non-mechanical where there is no movement, just a clicking sound. Clickers have been used by paratroopers , nuns and school teachers, dog trainers and who knows who else but they were most used in the hands of children to produce that wonderful repetitive and annoying sound that can drive parents wild.
Lithographed clickers or crickets as they are sometimes called were produced in Japan for their domestic market and for export around the world from 1920 or earlier. Many of the early clickers made in Pre-War Japan are the mechanical type. There are not as many different Pre-War clickers as there are whistles for some reason. Other countries produced clickers too: Germany made some wonderful mechanicals and sometimes these were copied by the Japanese.
Pre-War vintage clickers can usually be recognized by their more muted colors and a softer more painterly style of lithography with more detail than is usually seen on later post-war whistles.
Post-War Japanese Clickers-produced after World War 2
The variety of post war clickers leans much more to the non-mechanical. You will find many more of those produced, even into the 1970's. The mechanical ones probably became too expensive to manufacture around the mid 1960's and they did have those dangerous sharp edges.
The postwar period for clickers seems to starts with the Occupied Japan period. Unlike whistles, where I have not seen one marked made in Occupied Japan, I have come across clickers marked Occupied Japan. These are often hard to distinguish from the pre-war ones without the made in Occupied Japan mark.
Early 1950's clickers are close in look to many of the pre-war ones with the difference being the colors of the lithography. 1950's colors in Japanese tin of all kinds are very distinctive with red, orange, turquoise, lime green and a cream white predominating. The style of art often tends to excessive decoration, multiple patterns, incredible detail and more stuff crammed into a small space than you can imagine possible. On the best examples of early 1950's Japanese tin the surfaces of even the smallest toy can contain wild patterns, comic looking animals (dressed in detailed patterned clothes, of course), flowers, bugs, music staffs and musical notes.
The later post war clickers (1960's and after) are also colorful and can be filled with detail but as time goes on you will see more areas of solid color with less shameless excess. The colors also change, specifically the whites are brighter and more white than cream, the turquoise blues give way to royal or navy blue and darker greens replace the vibrant lime greens.