The audio cassette is relatively small and would easily fit in a shirt pocket. It is perhaps 3 inches across, 2 inches high, and 3/4 inch thick. It is slightly thicker at the bottom because of an area which is extended outward another 1/8 inch in the front and back of the cassette. It is apparently constructed of several parts, with the front and the back sections held together by several pins at different points.
The cassette itself is largely transparent, with some obscuring of vision by the fact that the substance which makes up the cassette is tinted and also not designed to be optically efficient. It is transparent enough for you to see inside where a ribbon of material is strung between two capstans, each of which surrounds a hole extending clear through the cassette. One side of the cassette holds all of the material at a point halfway down the height of the cassette, while the outer end of the ribbon reaches to the bottom of the cassette, around another capstan in the lower corner, across a series of open spaces at the bottom to a capstan in the opposite corner, and then extends up so as to be attached to the large opposing capstan halfway up the height of the cassette.
This material inside the cassette is pliable. If you pull it out of the bottom of the cassette, you can see that the side facing downward is shiny, while the opposing side is not. At the very center of the cassette, in the middle of the opening on the bottom of the cassette, the material crosses a small pad of non-abrasive material held in place by gold-colored bands and a holder the same shape as the pad itself. This mechanism gives if you press on it because it is held in place by the tension of a metal piece allowing some give in the pad. This pad holds the tape material away from the upper portion of the opening and also keeps the tape on either side away from the cassette housing as it comes from one capstan and reaches another.
The c...