Genetically develop a plant of which every part has a use. Say roots make potatoes, leaves are spinach, flowers are a show and seeds are to eat so were the fruits.

Make a PA system mic with sensor to track the face of the speaker. As he approaches the mic, its height will automatically be adjusted for his height.

Make bathing platform at a higher level with run off collected in a WC which could be used to flush toilet. It will save a lot of fresh water.

A number of youths hook on to porno sites due to curiosity to know about body of other sex. Make a body teacher club where volunteers will be available for visitor to learn by seeing and touching body parts. This will allay his curiosity and encourage healthy interaction.

Many trains have toilets with open drain. When it is at platform, the muck spoils the paltform vicinity. Make a tank with vent controllable by guard or driver. He will open them only when he sees that site is suitable for dumping.