I am a computer scientist looking to simulate a world wherein a public user can arbitrarily change size to explore the unexpected complexity of every-day objects on these various scales. The coding is not an issue, but the world requires data regarding what traversable objects would be useful to explore on a smaller scale, equivalent to enlarging every-day objects. The small scale regards a selected virtual user height between 1 centimeter and 1/10 of a centimeter tall, which distinguishes "small" from "microscopic."
Objects that are useful to for the general public to explore should have a structure observably different at this smaller but non-microscopic scale to the extent that observations show it no longer resembles the object at the original scale to a human observer. This rules out objects that are visually monotonous like simple liquids like olive oil and solids like glass which are recognizable at this small scale and the original scale. However, a special exception will be made for crystalline structures to include objects such as granules of sugar which have a drastically greater detail observed from at this scale.
As a standard, you can use objects that have a natural roughness of P40 or lower, otherwise translated as an average particle diameter of 425 micrometers or greater that can be traversed by a human at that scale.
An answer to this question is finite and observable. As stated, it only requires a statement of any objects meeting this criteria greater than 1 object.