King Kong vs Godzilla Ad Mat / Mold (National Screen Service, 1963)

Front of Ad Mat

Quick technology history lesson:  there was a time when movie studios or distribution companies offered "Ad Mats" (also called "Ad Molds"), which were shallow trays made of compressed wood fibers.  Inside of these mats were detailed, reversed images of advertisements of various sizes.  Molten lead was poured inside of these trays (by the user), which, when cooled, would result in a block that could be mounted in the setup of a printing press, allowing the user to print advertisements for that film!

Now, as mind-blowing as all of that is, I will say that the above explanation was collected from various websites that I read on the subject, and that brief synopsis is pretty much all of the information I could find.  I'd be open to any further details that anyone would share, especially if you ever worked with these in your job! I read that they often didn't survive, especially if they were used, which makes sense.

Back of Ad Mat

This particular item is just a little bigger than a magazine-sized backing board, and it's a light pinkish color (the color often varied, from what I have seen).  There are two square spaces on the right side that appear to be empty, or simply flat, but when you turn them in the light, you can see that they hold some finely-detailed images, which were promotional photos.  You can see this in the first photo above, but here are two close-ups.  You can pretty much discern the complete images:

Eventually, of course, this technology was replaced, so what was the last Godzilla movie to offer ad mats?  Available pressbooks mention "ad mats" all the way through GODZILLA VS. THE SMOG MONSTER!  In fact, GODZILLA VS. MEGALON is the first pressbook to exclude mention of ad mats, so they disappeared sometime between 1972 and 1976, as best I can tell!