* The material has small openings or obstacles: If light passes through a narrow slit or around a small object, it will spread out due to diffraction. This is because the light waves bend around the edges of the obstacle.
* The material is not perfectly smooth: If the surface of the material is rough or uneven, the light will scatter in different directions. This is called diffuse reflection.
So, the material itself could be anything, but it needs to have one of the following properties:
* It has small openings or obstacles: This could be a piece of cloth, a diffraction grating, or even a pinhole camera.
* It has a rough surface: This could be a piece of frosted glass, a piece of paper, or a wall painted with a rough texture.
Let me know if you want to learn more about diffraction!
