One of the most important aspects of an integrating sphere's operation, is that light is completely reflected inwards by the casing. Here you can see a test of the basic polystyrene sphere's internal reflectance. There is no reflective coating inside the sphere. Light has been injected through a small hole using the green LED torch visible at the top of the sphere.
You can clearly see light escaping though the 20 mm polystyrene wall. However, you can also see that the sphere is equally illuminated everywhere. This verifies that the sphere is integrating the light source as expected. This will ensure a uniform light distribution onto the CMOS photo detector (ip web cam) within the sphere.