What materials can form shadow?

Answer 1

Any material that prevents light from passing through will form a shadow. Walking down a street on a sunny day, your body will cast a shadow. On a sunny day, even passing clouds can cast a shadow on a hillside. So the list would be considerable.

Answer 2

Any material that does not allow light to pass through it can form a shadow. Common examples include opaque objects like wood, metal, plastic, and fabric. The darker and denser the material, the more distinct the shadow it will create.