How can i make a working model for natural resources and their conservation

Water conservation, harvesting rain water, bio-fencing to safeguard soil erosion and water preservation, tree planting, minimising the use of electricity and oil (petroleum products), recycling the solid and liquid wastes as far as possible, minimise the use of plastics (do away with the use of such plastics which can not be recycled), never pollute your surroundings, etc. You can make models related to the above themes, making use of locally available cheap and waste materials. For example, make model of biogas plant, which converts the bio- degradable waste into useful gas to be used as gas in the kitchen or as power to burn light. Soil erosion prevention model can also be prepared without much expense. Mud and grass can be used for this. Perhaps, you can search the sites related to appropriate technology.