I didn't come up with this, but you can search the AZ forum for pictures. I took three strips of carpet and expoxied the ends together to form a triangle with carpet side facing out. Then wedge that in the bucket, but leave room for the buffer to rotate freely.
If you don't have extra carpet lying around, go home depot and look for the strips of carpet for stairs. They're pre-cut and have a stiff backing that is perfect for this. You can add more strips to create more partitions.