How to keep a child busy for hours in the summer: DIY: Giant Ice Cube Awesomeness - filled with plastic animals, dinos, and such. And I'm sure you could put in food dye before its frozen to color it like the ice block in the photo.
Use card board to make a large circle with the brim in the middle . Use oak tag or cereal ENTRADA PARA DECIR EN QUE MESA ESTÁN boxes to make a cone shape for the top of the hat. Cut pieces for the eyebrows and mouth and tape together.