Tape the two bottles together. Place the elastic band around the two top ends. Put your lolly stick through the centre of the band and hold it in place by wrapping the smaller band around it. Wind up your lolly stick and check it turns OK, trim down if necessary. Cut your Ice cream tub lid to the right size and glue or tape it to the top of the bottles. Glue on a upside Margarine tub for the wheel house. Glue on your tube for the funnel. Wind up your band and have a bath or visit a pond! The steamer will propel itself across the water. Hints: You may need to adjust the 'Draft' (How deep it sits in the water) of the steamer so that the paddle is in the water. This is done by adding some water to the bottles. This exact method is used in real ships and called 'Ballasting'.
To make the Steamer go further and slower try to regulate the speed of the paddle by attaching a plastic flap to the bottle that the paddle pushes against each time it turns.
If you visit a lake or pond attach a long piece of string to the steamer so you can pull it back at the end of its journey