Why do you think most models show the scale sizes of the planets but do not show the scale distances between the planets?

Explanation:

If both distance and size are proportional to that in the solar system, the model would be essentially useless.

For example, if the sun were represented by a marble 1 cm in diameter, the planet Neptune would be represented by a grain of sand .3 mm in diameter about 32.3 meters (106 ft) away. The largest planet, Jupiter, would be a larger sand grain, 1 mm in diameter, about 5.6 meters from the sun. Earth would be less than 0.1 mm in diameter, about 1 meter away from the sun.

Such a model would barely fit into a gymnasium (basketball court), and the elements of it would be very difficult to find without a map.

r = ρ x length / area  

ρ = r x area / length  

ρ is in ohm-meters  

in basic units, it is m³kg/s³a²  

i think this is it.