Flexible protractor won't work. since the ball is round it wont give you the correct answer. One flaw is it won't lay flat on the ball very well, even if it is flexible, you'd need 3 hands to try and hold it flat at every important place to try and read it, but the angle it reads is based on a distance apart on the circumference of the protractor, but that gets distorted because of the roundness of the ball. If you were to draw 2 lines a 90 degree angle apart on a ball, and then try to lay the protractor down on the vertex of the 2 lines and then roll it down the ball to measure it, you wouldn't read it as a 90 degree angle, but something smaller than it. Measuring angles on a round surface is tricky. This is why on a bowling ball you can draw a triangle made of 3 90 degree angles, which wouldn't work on a piece of paper where the angles have to add up to 180 degrees.
