Rod and cords

This could be presented either as a puzzling trick, or simply as a novelty. At first glance the rod has three lengths of cord running through it. Closer inspection reveals that a length of cord is different on each side of the rod. For example, the cord in the middle in the illustration is green at the top and white at the bottom. If you hold the white end of the cord and pull it through the rod, you would expect the cord passing through the rod to come out green, but instead it mysteriously comes out white. The cords running through the rod at its end behave in a similar colour changing manner. The rod apparently has magical properties that allow it to change the colour of the cords as they are pulled backwards and forwards through it.