Together, we filmed the animation using an iPhone and a camera stand contraption. It was crucial that the camera and the model didn't move too much for this to work. Of course, since it's actually impossible to have an impossible staircase, we had to make sure the angle of the camera was just right. Another thing was that right at the point of deception, the ball would suddenly jump from a low point to a higher point, making it seem larger, and we had to account for the size of the ball as well to ensure that the gif would loop seamlessly. In the end it turned out all right, after several tries!