Pling-Plong Mechanism (top)
The actual dimensions of the device (without crank) are about 3.5 by 2.5 by 1 inches. The cardboard strips are fed in through the top, underneath the upper plate (with straight spring-bars that hold the card tightly against the mechanism), and underneath the red roller, which pulls the card through the device. Through the three holes near the roller, you can see a few of the comb teeth. Also note the mounting holes, which allows one to screw the pling-plong into any housing desired. Let me also mention that this mechanism is *heavy* for its small size, and is extremely solid and well-built. Not the kind of thing one would necessarily expect from Sankyo.
Pling-Plong Mechanism (side)
Here you can see the 20 spring-wheels which pluck the 20 notes of the comb, as the hole-punched cards pass over them. The scale is a C-major (or A-minor) scale, from a low C (on the right) through 2 octaves, up to an A above the third C (on the left).
Here is a pling-plong card which was blank before I began punching Brahms'Lullabye onto it. The holes are about 2 millimeters in diameter, and the card is about 2.5 inches on the short side by about 10 inches on the long side (but of course, you could tape many cards together to make a long composition.) I like how the notes are printed along the x-axis of the grid, and how there's even a musical staff printed right on the card, which corresponds to the positions of the notes. These guides make it easy to arrange simple compositions, or create your own!