Children will wind this toy up and then the gear box will run and simultaneously move the paddle wheel and dry land wheels. This allows the toy to smoothly transition from land to water and back.
The principle this toy is based on is buoyancy and motion. It will float and move. With movement on both land and in water.
a brief discussion of construction cost, durability and safety.
This toy will be fairly inexpensive to produce. The inside will be filled with foam to help it float. The winder will have to be plastic with stainless steel to ensure the toy does not rust and the parts will have to be watertight. The most expensive part of this toy will be the gearbox which can be taken from a stock system and modified.
This toy will be watertight and thus if used as expected will be very durable. It won't be able to withstand very much abuse due to the fact it has to be light enough to float.
This toy will have small parts and thus will be for ages 4+. Other than that there are not many saftey issues that arise.