Now keeping everything covered with the plastic rub the fibres in a circular motion to tangle them. Gently at first then with more force. Do this on both sides and pay particular attention to the edges. You should be able to feel the cardboard edge through the fibres. If you let the two sides felt together at the edge you will have a ridge in the finished hat.
This step will be quite exhausting as you have to keep going until the fibres are matted in to place.
Now sit down and have a break. I will be back tomorrow.