So Guys what sort of vehicle should these happy little tread units go to? While I have a couple of ideas, I figured I would ask.
As for their construction they are dead easy to make. Use a round punch to form the "wheels". Then Laminate them to a bit of backing plastic card, and trim the plastic card to the shape of the tread unit flush with the wheels. Finally using a bit of flexible plastic card, in this case 1/4 by 0.01 strip, glue it in place around the wheels.
Additional track detail can be added at this point. I have considered lugs in the form of small T shaped rod. But simple raised plates wouldn't be much of a trick either.