Due to a non-disclosure agreement, I can't provide a whole lot of details about it. Picture a neutrally buoyant balloon, floating at a fixed point in the air. I want to measure its roll angle as it drifts from side to side. I don't really care about its y or z axis', or its acceleration. I just want to theoretically take a construction level, place it on the balloon and see how much it's deviated from a level position. There will be no fixed point on the balloon as it is floating, so nothing will be able to spin the pot as it rotates.